JP2018049116A - Contact/separation mechanism and image formation apparatus using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve the contact/separation operation of a movable member by using the rotational force following driving rotation of a rotor.SOLUTION: A contact/separation mechanism includes: a first drive transmission member 3 to which the rotational force of a rotor 1 is transmitted and which is rotationally driven with the rotation center as the center; a second drive transmission member 4 which is held at the initial position when the rotor 1 does not perform driving rotation, rotated with the rotation center as the center when the rotor 1 performs driving rotation, and moved to the rotor 1 side along the rotation center axial direction; a support member 5 which supports a movable member 2 in a manner of being capable of contacting/separating between the contact position P1 where the movable member 1 contacts the peripheral surface of the rotor 1 and the retreat position P0 where the movable member 2 retreats; and a displacement mechanism 6 which is provided between the second drive transmission member 4 and the support member 5, engaged with the support member 5 when the second drive transmission member 4 is moved from the initial position along the rotation center axial direction, presses the support member 5 toward the direction of approaching the peripheral surface of the rotor 1, and displaces the movable member 2 to the contact position P1.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an approach / separation mechanism and an image forming apparatus using the contact / separation mechanism.

Conventionally, the following is already known as a method of contacting and separating a roll member having an elastic layer with respect to a photoconductor arranged opposite to the roll member.
Patent Document 1 discloses a configuration including a separation cover for separating the charging roll from the photosensitive member during packaging and use in order to prevent unnecessary deformation of the charging roll.
Further, in Patent Document 2, in an aspect including a transfer roll provided with a photoconductor and a conveyance belt sandwiched therebetween, the transfer roll is moved to a position facing the photoconductor by the movement of the conveyance belt, and is returned to the original state after the stop. A configuration is disclosed.
Further, in Patent Document 3, a helical gear meshing with a drum gear of a photosensitive member and a chipped gear are used, and a gap state between the photosensitive member and the charging roll is maintained between the photosensitive member and the charging roll by the chipped gear. A configuration is disclosed in which the toothless gear is rotated by the rotation of the gear, and a contact state is formed between the two, and further, the stopper member is protruded by the movement of the helical gear to restrict the rotation of the toothless gear.

JP 2007-271759 A (Best Mode for Carrying Out the Invention, FIG. 2) JP 2010-210922 A (form for carrying out the invention, FIG. 6) JP 2001-109356 A (Example 1, FIG. 10)

  The technical problem to be solved by the present invention is that in a mode in which the movable member is brought into contact with and separated from the peripheral surface of the rotating body capable of being driven and rotated, the rotational force accompanying the driving rotation of the rotating body is used to contact the movable member. It is to realize the separation operation.

  The invention according to claim 1 is an approach / separation mechanism that contacts and separates the movable member with respect to the circumferential surface of the rotating body that can be driven to rotate, and is provided on the end in the width direction that intersects the rotational direction of the rotating body. A first drive transmission member that is rotationally driven around a rotation center by transmitting a rotational force of the rotary body, and a first drive transmission member that is provided so as to be related to the first drive transmission member, and the rotary body does not rotate. The rotary member is held at a predetermined initial position, and when the rotating body is driven to rotate, the rotational force of the first drive transmission member is transmitted to be rotationally driven around the rotational center and along the rotational central axis direction. The movable member is contacted and separated between a second drive transmission member moved to the rotating body side, a contact position where the movable member contacts the peripheral surface of the rotating body, and a retracted position where the movable member retracts. A support member that supports the second member; Provided between the motion transmission member and the support member, and when the second drive transmission member is moved from the initial position along the rotation center axis direction, the support member is engaged, A contact / separation mechanism comprising: a displacement mechanism that presses in a direction approaching the peripheral surface of the rotating body and displaces the movable member at the contact position.

According to a second aspect of the present invention, in the contact / separation mechanism according to the first aspect, the first drive transmission member, the second drive transmission member, the support member, and the displacement mechanism are arranged in a rotational direction of the rotating body. The contact / separation mechanism is provided at each of both ends of the intersecting width direction.
According to a third aspect of the present invention, in the contact / separation mechanism according to the first or second aspect, the first drive transmission member and the second drive transmission member are constituted by helical gears that mesh with each other. This is a contact / separation mechanism.
According to a fourth aspect of the present invention, in the contacting / separating mechanism according to the first or second aspect, the second drive transmission member is biased so as to be held at the initial position when the rotating body does not rotate. An urging member including a biasing member.
The invention according to claim 5 is the contact / separation mechanism according to claim 4, wherein the urging member is accommodated in the support member.
The invention according to claim 6 is the contacting / separating mechanism according to claim 1 or 2, wherein the displacement mechanism is provided separately from or integrally with the second drive transmission member, together with the second drive transmission member. An axially movable portion that moves toward the support member along the rotation center axis direction of the second drive transmission member, and the movable member is moved via the support member as the axially movable portion moves. An approach / separation direction movable part that moves from the retracted position to the contact position, and at least one of the axial direction movable part or the contact / separation direction movable part is directed in a direction approaching the peripheral surface of the rotating body. And a contact / separation mechanism having a pressing portion for pressing the support member.
The invention according to claim 7 is the contacting / separating mechanism according to claim 6, wherein the displacement mechanism has one displacement member in which the axially movable portion and the contacting / separating direction movable portion are integrated, and the support The axially movable portion is guided while sliding with respect to a member, and the support member is pressed toward a contact position of the movable member by a pressing portion provided in the movable portion in the contact / separation direction. It is an approach / separation mechanism.
The invention according to claim 8 is the contacting / separating mechanism according to claim 6, wherein the displacement mechanism is configured such that the axially movable part and the approaching / separating direction movable part are formed separately, and the axially movable part and the The contact / separation mechanism is characterized in that the pressing portion is provided at a portion where the movable portion in the contact / separation direction is engaged.
The invention according to claim 9 is the contacting / separating mechanism according to claim 1 or 2, wherein the displacement mechanism is configured such that the support member is moved to the movable member when the second drive transmission member returns to the initial position. It is an approach / separation mechanism characterized by having a return mechanism for returning to the retracted position side.
According to a tenth aspect of the present invention, in the contact / separation mechanism according to the ninth aspect, the return mechanism of the displacement mechanism is arranged in parallel at a position substantially parallel to the rotation center axis of the second drive transmission member, and the second mechanism When the drive transmission member returns to the initial position, the rotation center axis of the second drive transmission member as viewed from the photosensitive member side deviates from the center axis of the movable member in the direction along the width direction of the rotation body. It is the contact-and-separation mechanism characterized by being arrange | positioned.
According to an eleventh aspect of the present invention, in the aspect of the contact / separation mechanism according to any one of the first to tenth aspects, the movable member is a rotatable rotating member, and the supporting member is the rotating member as the rotating member. The contact / separation mechanism is provided on a bearing that is rotatably held.
According to a twelfth aspect of the present invention, there is provided a latent image holding body that holds an electrostatic latent image, a charger that charges the latent image holding body to form an electrostatic latent image, and a static image on the latent image holding body. A developing device that develops the electrostatic latent image with a developer, a transfer device that develops the latent image on the latent image holding member and that is developed on the latent image holding member, and a transfer device that is transferred by the transfer device. A cleaning device that cleans the subsequent latent image carrier, and the latent image carrier is a rotating body, and at least one of the charger, the transfer device, and the cleaning device is a movable member. An image forming apparatus using the contact / separation mechanism according to claim 1 as the contact / separation mechanism between the two.

According to the first aspect of the present invention, in the aspect in which the movable member is brought into contact with and separated from the circumferential surface of the rotating body that can be driven and rotated, the moving force is brought into and out of the movable member by using the rotational force accompanying the drive rotation of the rotating body. Can be realized.
According to the invention which concerns on Claim 2, compared with the aspect which provides a 1st, 2nd drive transmission member, a support member, and a displacement mechanism only in the one end part side in the width direction of a rotary body, a rotary body and a movable member are included. The separation interval can be kept wide, and can be easily applied to a long movable member.
According to the invention which concerns on Claim 3, the movement along the rotating shaft center direction of the 2nd drive transmission member is realizable by simple structure.
According to the fourth aspect of the invention, the second drive transmission member can be easily returned to the initial position.
According to the invention which concerns on Claim 5, compared with the aspect which provides an urging member in the exterior of a supporting member, the downsized contact / separation mechanism is realizable.
According to the invention which concerns on Claim 6, the displacement which goes to a contact position from a retracted position with respect to a support member is realizable with a simple structure.
According to the invention which concerns on Claim 7, the displacement mechanism which used the axial direction movable part and the approach / separation direction movable part as one displacement member is easily realizable.
According to the invention which concerns on Claim 8, the displacement mechanism which makes an axial direction movable part and an approach / separation direction movable part separate can be implement | achieved easily.
According to the ninth aspect of the present invention, the movable member can be retracted to the retracted position when the rotating body is not driven, regardless of the arrangement of the movable member with respect to the rotating body.
According to the invention which concerns on Claim 10, even if it is the aspect which arrange | positions the return mechanism of a displacement mechanism in parallel in the position substantially parallel to the 2nd drive transmission member, a return mechanism and a support member are not enlarged. Can be ensured.
According to the invention which concerns on Claim 11, a movable member can be contacted / separated in the state which hold | maintained the rotatable movable member.
According to the twelfth aspect of the present invention, in the aspect in which the movable member is brought into contact with and separated from the peripheral surface of the rotating body that can be driven and rotated, the moving force is brought into and out of the movable member by using the rotational force accompanying the driving rotation of the rotating body. An image forming apparatus capable of realizing the above can be provided.

(A) is explanatory drawing which shows the outline | summary of the contact-and-separation mechanism in the outline | summary of embodiment which concerns on this invention, (b) (c) is explanatory drawing which shows the different aspect of a displacement mechanism. 1 is an explanatory diagram showing an overview of an image forming apparatus according to Embodiment 1. FIG. FIG. 3 is an explanatory diagram illustrating an aspect at a retracted position of the photosensitive member and the transfer roll in the first embodiment. FIG. 5 is an exploded perspective view of FIG. 4. FIG. 3 is an explanatory diagram illustrating a main part of a transfer roll contact / separation mechanism according to Embodiment 1; 2A and 2B are explanatory diagrams illustrating contact and separation states between the photosensitive member and the transfer roll in Embodiment 1, where FIG. 3A illustrates a retracted position, and FIG. 3B illustrates a state at the contact position. 2A and 2B are views of the transfer roller side as viewed from the photoconductor side in the first embodiment, where FIG. 3A shows a retracted position, and FIG. 2A and 2B are perspective views showing a contact state of the photoconductor and the transfer roll in Embodiment 1, where FIG. 3A shows a retracted position, and FIG. 2B shows a state at the contact position. 3 is an explanatory diagram illustrating a power feeding mechanism to a transfer roll used in Embodiment 1. FIG. 2A and 2B are cross-sectional views at the position of a U groove portion of the transfer housing according to the first embodiment, where FIG. 3A shows a retracted position, and FIG. FIG. 6 is an explanatory diagram showing a main part of a transfer roll contacting / separating mechanism according to Embodiment 2, wherein (a) shows a retracted position and (b) shows a state at the contact position. FIG. 10 is an explanatory diagram showing a main part of a support member and a displacement mechanism used in Embodiment 2. FIG. 5 is an explanatory diagram showing a contact / separation state between a photoconductor and a transfer roll in Embodiment 2, where (a) shows a retracted position and (b) shows a state at the contact position. 4A and 4B are diagrams of the transfer roller side as viewed from the photoconductor side according to the second embodiment, where FIG. FIG. 6 is a perspective view showing a contact state of a photoconductor and a transfer roll in Embodiment 2, where (a) shows a retracted position and (b) shows a state at the contact position. FIG. 10 is an explanatory diagram illustrating an overview of an image forming apparatus according to a third embodiment. FIG. 6 is an explanatory diagram showing a contact / separation state between a photoconductor and a transfer roll in Embodiment 3, where (a) shows a retracted position and (b) shows a state at the contact position.

Outline of Embodiment FIG. 1A is an explanatory diagram showing an outline of the contact / separation mechanism in the outline of the embodiment according to the present invention. In the same figure, the contact / separation mechanism is for contacting / separating the movable member 2 with respect to the circumferential surface of the rotator 1 that can be driven and rotated, and is provided on the end in the width direction crossing the rotation direction of the rotator 1. The first drive transmission member 3 that is driven to rotate about the rotation center by transmitting the rotational force of the rotary body 1 and the first drive transmission member 3 are provided so that the rotary body 1 is driven to rotate. If not, it is held at a predetermined initial position, and when the rotating body 1 is driven to rotate, the rotational force of the first drive transmission member 3 is transmitted to rotate following the rotation center and in the direction of the rotation center axis. Movable between the second drive transmission member 4 moved to the rotator 1 side, the contact position P1 where the movable member 2 contacts the peripheral surface of the rotator 1, and the retracted position P0 where the movable member 2 retracts. Support member 5 for supporting member 2 so as to be able to come into contact with and away from it, and a second drive transmission portion 4 and the support member 5. When the second drive transmission member 4 is moved from the initial position along the rotation center axis direction, the support member 5 is engaged with the support member 5. And a displacement mechanism 6 that presses in a direction approaching the peripheral surface of 1 and displaces the movable member 2 to the contact position P1.

  Here, the rotating body 1 includes not only a drum shape but also a belt shape, and a representative aspect of the movable member 2 includes a rotating member, but is not limited thereto. And a non-rotating member. Further, the first drive transmission member 3 and the second drive transmission member 4 are typically provided adjacent to each other. However, the present invention is not limited to this, and other members are sandwiched between them. There is no problem.

  Moreover, as a typical aspect of the supporting member 5, a bearing in an aspect in which the movable member 2 is a rotating member is exemplified. The first and second drive transmission members 3, 4, the support member 5, and the displacement mechanism 6 may be provided on both ends in the width direction of the rotating body 1, or may be provided only on one side. May be. Further, the displacement mechanism 6 may be composed of a plurality of members, and a part thereof may be provided on the second drive transmission member 4 side.

  Further, between the rotating body 1 and the movable member 2, if the movable member 2 can be displaced between the retracted position P0 and the contact position P1, the rotating body 1 and the movable member 2 at the retracted position P0. The aspect arrange | positioned in parallel may be sufficient, and the aspect by which the movable member 2 was arrange | positioned diagonally with respect to the rotary body 1 may be sufficient.

Next, a typical aspect or a preferable aspect of the contact / separation mechanism in this aspect will be described.
From the viewpoint of keeping a large separation distance between the rotating body 1 and the movable member 2, the first drive transmission member 3, the second drive transmission member 4, the support member 5, and the displacement mechanism 6 intersect the rotation direction of the rotation body 1. The aspect currently provided in the width direction both ends side to do is mentioned, respectively. For example, in an aspect in which these members are provided only on one side of the rotating body 1 and the movable member 2, particularly when the length of the rotating body 1 and the movable member 2 is long, the rotating body 1 and the movable member 2 at the retracted position P0 It is necessary to ensure a large separation interval, and accordingly, the amount of displacement of the movable member 2 from the retracted position P0 to the contact position P1 increases, and the contact / separation mechanism itself is easily increased in size.

  Further, as a mode for further simplifying the contact / separation mechanism, a mode in which the first drive transmission member 3 and the second drive transmission member 4 are constituted by helical gears that mesh with each other can be cited. By meshing the two helical gears, movement in the direction along the central axis of rotation (thrust direction) is facilitated.

  Further, in order to hold the second drive transmission member 4 at the initial position, the second drive transmission member 4 is biased so as to be held at the initial position when the rotating body 1 is not driven to rotate. The aspect containing is mentioned. Such an urging member may be provided adjacent to the second drive transmission member 4 or may be provided via another member. From the viewpoint of reducing the size of the contact / separation mechanism, an embodiment in which the urging member is accommodated in the support member 5 can be mentioned.

  Further, as a representative aspect of the displacement mechanism 6, the second drive transmission member 4 is provided separately from or integrally with the second drive transmission member 4, and the second drive transmission member 4 and the rotation center axis direction of the second drive transmission member 4 are provided. An axially movable portion 7 that moves toward the support member 5 along the contact direction, and a contact / separation direction in which the movable member 2 is moved from the retracted position P0 to the contact position P1 via the support member 5 as the axially movable portion 7 moves. A pressing portion 6a that presses the support member 5 in a direction approaching the circumferential surface of the rotating body 1 at least at one position of the axially movable portion 7 or the approaching / separating direction movable portion 8. An embodiment is mentioned.

  Here, the axial direction movable part 7 and the contact / separation direction movable part 8 may be integrally formed, or may be separate. In other words, the configuration of the displacement mechanism 6 is not particularly limited. For example, as shown in FIG. 1B, the axially movable portion 7 and the contacting / separating direction movable portion 8 are integrally provided, and these are integrated. The support member 5 may be moved, and as shown in FIG. 1C, the axially movable portion 7 is provided on the second drive transmission member 4 side, and the contact / separation direction movable portion 8 is provided. It may be configured separately from the axially movable portion 7, and the axially movable portion 7 may abut against the contact / separation direction movable portion 8 so that the contact / separation direction movable portion 8 moves the support member 5.

  And the pressing part 6a should just be provided in either the axial direction movable part 7 or the contact / separation direction movable part 8. FIG. Here, although the pressing part 6a has a predetermined inclined surface, for example, it goes without saying that the inclination direction of the inclined surface is a direction in which the support member 5 faces the contact position P1 of the movable member 2.

Further, as a representative aspect of the displacement mechanism 6, as shown in FIG. 1B, the displacement mechanism 6 has one displacement member 9 in which the axially movable portion 7 and the contact / separation direction movable portion 8 are integrated, and the support member. The axial direction movable part 7 is guided while being slid with respect to 5 and the support member 5 is pressed toward the contact position P1 of the movable member 2 by the pressing part 6a provided in the contact / separation direction movable part 8. It is done. In this embodiment, the axially movable portion 7 and the contact / separate direction movable portion 8 are integrated into one displacement member 9, and the axially sliding portion 7 slides (slids and moves) with respect to the support member 5. ), And the movable portion 8 in the contact / separation direction may press the support member 5 toward the contact position P1 of the movable member 2. At this time, the axially movable portion 7 may be inserted into a guide hole provided inside the support member 5, or may be an embodiment covering the outside of the support member 5.
Moreover, as another typical aspect of the displacement mechanism 6, as shown in FIG.1 (c), the axial direction movable part 7 and the contact / separation direction movable part 8 are comprised separately, and the axial direction movable part 7 and The aspect which has the pressing part 6a in the site | part with which the contact / separation direction movable part 8 engages is mentioned. In this embodiment, the axially movable part 7 and the contact / separation direction movable part 8 are separated from each other, and the pressing part 6a is provided at the part where both are engaged, thereby making the contact / separation direction movable part 8 of the movable member 2 What is necessary is just to make it move toward the contact position P1.

Further, as a representative aspect of the displacement mechanism 6, a return mechanism (not shown) for returning the support member 5 to the retracted position P0 side of the movable member 2 when the second drive transmission member 4 returns to the initial position. The aspect which has is mentioned. In this example, the displacement mechanism 6 is provided with a return mechanism. For example, the movable member 2 is arranged in the upper half region of the rotating body 1 and the movable member 2 moves in the direction approaching the photoconductor 1 by its own weight. Even in this case, the movable member 2 can be held at the retracted position P0. Needless to say, a return mechanism may be employed for the mode in which the movable member 2 is disposed in the lower half region of the rotating body 1.
Furthermore, as a typical aspect of the return mechanism described above, when the second drive transmission member 4 returns to the initial position, the second drive transmission member 4 is arranged in parallel at a position substantially parallel to the rotation center axis of the second drive transmission member 4. The rotation center axis | shaft of the 2nd drive transmission member 4 seeing from the photoreceptor side and the aspect arrange | positioned with respect to the center axis | shaft of the direction along the width direction of the rotary body 1 of the movable member 2 are mentioned. In this example, when the return mechanism of the displacement mechanism 6 is arranged in parallel at a position substantially parallel to the second drive transmission member 4, the second mechanism is used to secure a space that facilitates engagement of the return mechanism with the support member 5. A mode in which the drive transmission member 4 and the movable member 2 are arranged in a biased manner is preferable. In this case, if the second drive transmission member 4 and the movable member 2 are not biased, the support member 5 must be enlarged in order to ensure the engagement between the return mechanism and the support member 5. There are limitations.

  Further, in the aspect in which the movable member 2 is a rotatable rotating member, the support member 5 is provided on a bearing that rotatably holds the movable member 2 as the rotating member from the viewpoint of smoothly rotating the movable member 2. The aspect which is mentioned is mentioned.

  In order to use the above contact / separation mechanism in the image forming apparatus, the following may be performed. That is, a latent image holding body that holds an electrostatic latent image, a charger that charges the latent image holding body to form an electrostatic latent image, and the electrostatic latent image on the latent image holding body as a developer A developing device that develops the toner image, a transfer device that transfers the image developed by the developing device and formed on the latent image holding member to a recording material, and the latent image held after being transferred by the transfer device. A cleaning device that cleans the body, and the latent image holding body is a rotating body 1 and at least one of the charger, the transfer device, and the cleaning device is a movable member 2. What is necessary is just to apply the above-mentioned as an approach / separation mechanism.

  Here, as a specific aspect of the image forming apparatus, the contact / separation mechanism described above with respect to an aspect in which the rotating body 1 is a photosensitive member and the movable member 2 is at least one of a charger, a transfer device, and a cleaning device. The aspect using is mentioned. Further, the image forming apparatus may include a process cartridge having a charger as the movable member 2. In particular, when at least one of the rotating body 1 and the movable member 2 has an elastic layer that is elastically deformed, the deterioration with time of the elastic layer can be further suppressed by arranging them in a non-contact manner when both are unnecessary.

Hereinafter, the present invention will be described in more detail based on embodiments shown in the accompanying drawings.
Embodiment 1
<Schematic configuration of image forming apparatus>
FIG. 2 is an explanatory diagram showing an outline of the image forming apparatus according to the first embodiment. In the figure, an image forming apparatus 10 according to the present embodiment is configured as a monochrome printer, and has an image forming unit 20 that forms an image on a recording material S at the approximate center in the apparatus housing 11. A recording material supply unit 12 that supplies the recording material S toward the image forming unit 20 is installed below the image forming unit 20.

  In the image forming unit 20, various elements for image formation are arranged around a photosensitive member 21 (corresponding to a rotating member) as a latent image holding member. Around the photosensitive member 21, a charger 22 for charging the photosensitive member 21 so that an electrostatic latent image can be formed, and an exposure unit 23 for drawing the electrostatic latent image on the photosensitive member 21 charged by the charger 22. The developing unit 24 that develops the developer with a developer so as to visualize the electrostatic latent image drawn by the exposure unit 23, and the developed image is transferred to the recording material S supplied from the recording material supply unit 12. A transfer unit 25, a cleaning unit 26 for cleaning the surface of the photoreceptor 21 after transfer, and the like are provided.

  The recording material supply unit 12 includes a supply cassette 13 in which a recording material S to be supplied is accommodated, and a separating mechanism 14 for feeding and feeding the recording materials S one by one from the supply cassette 13. The recording material S accommodated therein is appropriately fed out one by one toward the image forming unit 20. The recording material S fed from the recording material supply unit 12 is positioned by the resist roll 15 and then conveyed to a transfer site at a predetermined timing.

  The image transferred onto the recording material S at the transfer site is fixed by the fixing device 16 disposed above the apparatus housing 11, and the fixed recording material S fixed by the fixing device 16 is discharged. The paper is discharged to a recording material discharge unit 18 formed on the upper surface of the apparatus housing 11 by a roll 17.

<Relationship between photoconductor and transfer device>
In the present embodiment, as shown in FIGS. 3 and 4, the photosensitive member 21 has a photosensitive layer 21b on the peripheral surface of the aluminum base tube 21a, and both end portions of the aluminum base tube 21a are made of, for example, a synthetic resin. The flanges 32 are respectively closed, and the support shafts 33 are respectively projected from the centers of the flanges 32 so as to protrude outwardly. A bearing portion 36 is formed on the letter-shaped holding arm 35, and each support shaft 33 is rotatably held on the bearing portion 36.
On the other hand, as shown in FIGS. 3 to 5, the transfer unit 25 includes a transfer roll 40 having a configuration in which a metal core is wound with elastic rubber having a predetermined volume resistance value. At both ends of the roll 40, support shafts 41 are provided so as to protrude outward in the axial direction, and bearing holding portions 43 are formed on both sides in the axial direction of the transfer casing 42 for holding the transfer roll 40, respectively. The bearing holding portions 43 hold the bearings 44, and the respective support shafts 41 are rotatably held by the respective bearings 44. In this example, the transfer housing 42 is fixed to a device housing or a photoreceptor housing 34 (not shown), and the bearing holding portion 43 has a U-shaped groove (U) that opens toward the photoreceptor 21 side. Groove portion) 43a, and each bearing 44 is movable along the depth direction of the U groove portion 43a of the bearing holding portion 43. However, each bearing 44 is restrained in the position in the width direction intersecting the depth direction of the U groove 43a. Reference numeral 45 denotes a U-shaped flange projecting around the bearing 44, which functions as a stopper when the bearing 44 is held in the U-groove 43a.
Here, if the photosensitive member 21 and the transfer roll 40 are placed in contact with each other for a long time, for example, a plasticizer from the elastic rubber may ooze out and adversely affect the photosensitive layer. May be deformed. When such a situation occurs, the conditions of the photosensitive layer 21b of the photosensitive member 21 change or the transfer conditions of the transfer roll 40 change, which adversely affects image formation. Therefore, as a countermeasure against such a problem, in the present embodiment, the photosensitive member 21 and the transfer roll 40 are brought into contact with each other when necessary, and the two are arranged in a non-contact manner when unnecessary. A contact / separation mechanism 50 is adopted between the roll 40.

<Outline of contact / separation mechanism>
In the present embodiment, the contact / separation mechanism 50 moves the transfer roll 40 to a contact position P1 that contacts the photoconductor 21 when the photoconductor 21 rotates as shown in FIGS. The transfer roll 40 is moved to the retracted position P0 retracted from the photoreceptor 21 when 21 is in a stopped state.
In this example, the contact / separation mechanism 50 includes a first helical gear 51 as a first drive transmission member provided coaxially with the support shaft 33 outside the flange 32 of the photosensitive member 21, and the first helical gear 51. A second drive transmission member that is arranged in parallel with the rotation axis of the helical gear, meshes with the first helical gear 51, rotates following, and moves in a direction approaching the end of the transfer roll 40. As a second helical gear 52 and a bearing 44 of the transfer roll 40, and a support member 53 that supports the bearing 44 so that the transfer roll 40 can contact and separate from the photosensitive member 21. And the second helical gear 52 and the support member 53 are disposed at the retracted position P0 when the second helical gear 52 approaches the end of the transfer roll 40. Displacement mechanism 5 for displacing the transfer roll 40 toward the contact position P1 It has a, and.

-First and second helical gears-
In this example, the first helical gear 51 is formed by integrally forming a ring-shaped gear main body having a diameter larger than the outer diameter of the flange 32 with the flange 32, and the peripheral surface of the gear main body with respect to the rotation shaft. The teeth are cut in the direction twisted diagonally.
Further, as shown in FIGS. 3 and 4, the second helical gear 52 has a rotation shaft 52b extending outward in the axial direction at the center of the gear main body 52a (see FIG. 6), and a photoconductor. The rotating shaft 52b is held by the holding arm 35 of the housing 34 so that the rotating shaft 52b can be rotated by the bearing portion 37 formed in advance alongside the bearing portion 36 and the axial movement of the rotating shaft 52b is allowed. is there. On the other hand, an overhanging portion 52d that protrudes toward the end portion of the transfer roll 40 is formed on the surface of the gear body 52a opposite to the rotation shaft 52b.
In this example, the meshing state of the first helical gear 51 and the second helical gear 52 is such that when the first helical gear 51 is rotationally driven in a predetermined direction. When the second helical gear 52 rotates following this, the axial load (thrust load) acting on the second helical gear 52 acts toward the end of the transfer roll 40. Selected. In this example, the rotating shaft 52b is disposed so as to penetrate the bearing portion 37. However, the distal end portion of the rotating shaft 52b has a flange portion 52c formed in a slit shape, and the rotating shaft 52b is the bearing portion. 37, and serves as a stopper when sliding along 37. Furthermore, the overhanging portion 52d is configured as a cylindrical portion having a diameter smaller than the outer diameter of the gear body 52a with the center of the gear body 52a as the center.

-Support member-
In the present embodiment, the bearing 44 of the transfer roll 40 is formed of a molded product made of, for example, a conductive resin, and has a cylindrical recess that rotatably holds the support shaft 41 of the transfer roll 41.
In this example, the support member 53 is integrally formed with the bearing 44, and a cylindrical connecting tube extending toward the second helical gear 52 with the partition wall of the cylindrical recess of the bearing 44 interposed therebetween. It has a body 61. The connecting cylinder 61 has an opening on the second helical gear 52 side, and a pair of elongated holes 62 extending in the axial direction of the second helical gear 52 are formed at opposing portions of the peripheral wall. is there.

-Displacement mechanism-
In the present embodiment, as shown in FIG. 5, the displacement mechanism 54 is provided separately from the second helical gear 52, and together with the second helical gear 52, the second helical gear 52. An axially movable portion 70a that moves toward the support member 53 along the rotation axis direction, and the transfer roll 40 is moved from the retracted position P0 to the contact position P1 via the support member 53 with the movement of the axially movable portion 70a. And a movable member 70b in the contact / separation direction, and the movable member 70a in the axial direction and the movable member 70b in the contact / separation direction are integrated with a synthetic resin.
In this example, the axially movable portion 70 a of the displacement member 70 has a columnar rod 71 inserted into the connecting cylinder 61 of the support member 53, and the rod 71 has a second helical gear 52 side. Is formed with a flange 72 and a pair of stopper projections 73 slidable along the elongated hole 62 of the connecting cylinder 61 on the peripheral wall of the rod 71. The stopper protrusion 73 of this example has a tapered surface 73 a that narrows toward the connecting cylinder 61, and the stopper protrusion 73 opens the opening of the connecting cylinder 61 when the rod 71 is inserted into the connecting cylinder 61. It enters into the connecting cylinder 61 while elastically deforming the vicinity thereof, and is fitted into the long hole 62 of the connecting cylinder 61, and the stopper projection 73 hits the terminal end of the long hole 62, thereby This prevents the rod 71 from coming off. Moreover, the collar part 72 hits the opening edge part of the connection cylinder 61, and the insertion amount to the connection cylinder 61 of the rod 71 is controlled.
Further, in the present embodiment, a coil spring 80 for urging the rod 71 in the disengagement direction is incorporated in the connecting cylinder 61, and the second helical gear 52 is returned to the initial position as will be described later. It works when you do.

  In addition, the movable portion 70b in the contact / separation direction of the displacement member 70 is integrally formed so that a substantially L-shaped push-up arm 75 extends from a part of the flange portion 72 of the rod 71 toward the end portion side of the transfer roll 40. A wedge-shaped push-up portion 76 is provided at the tip of the push-up arm 75. The push-up portion 76 of this example has an inclined surface 77 that is inclined so as to approach the contact position P1 side of the transfer roll 40 toward the tip. An abutting wall 78 is provided at the tip of the substantially L-shaped holding arm 35 of the photoconductor housing 34 at a portion facing the push-up portion 76 of the push-up arm 75, and a corner 78 a of the abutting wall 78. (See FIG. 8) has a chamfered structure. Further, the push-up portion 76 of the push-up arm 75 is disposed at a position where the inclined surface 77 abuts against the corner portion 78 a of the abutment wall 78, and the push-up portion 76 of the push-up arm 75 abuts against the abutment wall 78. Further, when pushed forward, the push-up portion of the push-up arm 75 rides on the top of the pushing wall 78 along the inclined surface 77 so that the position of the push-up arm 75 as a whole is displaced to the contact position P1 side of the transfer roll 40. It has become.

-Power supply mechanism-
In the present embodiment, as shown in FIGS. 4 and 9, a power supply mechanism 90 that supplies power to the transfer roll 40 is provided. In the power supply mechanism 90, power supply component holding projections 38 and 39 are formed in advance on a part (two locations in this example) of the holding arm 35 of the photosensitive member casing 34, and one power supply component holding projection 38 is formed. The base 91a of the torsion spring 91 as a power supply component is hooked, and the contact piece 91b of the torsion spring 91 is elastically brought into contact with the peripheral surface of the bearing 44 made of conductive resin. The torsion spring 91 is pulled out to a portion facing the outside of the holding arm 35 via the lead wiring portion 92, and the holding arm is hooked by one end portion of the lead wiring portion 92 to another power supply component holding projection 39. 35 is attached. For this reason, according to the power supply mechanism of this example, power is supplied to the transfer roll 40 via the torsion spring 91 and the bearing 44 that are power supply components by using one end portion of the lead-out wiring portion 92 as a power supply point. ing.

<Contact / separation operation by contact / separation mechanism>
Next, the contact / separation operation between the photoreceptor 21 and the transfer roll 40 will be described.
First, in the present embodiment, as can be seen from FIG. 2, the transfer roll 40 is configured to be positioned vertically downward with respect to a horizontal line passing through the center of the photosensitive member 21. For this reason, the transfer roll 40 easily maintains a non-contact state where the transfer roll 40 is in the retracted position P0 with respect to the photosensitive member 21 due to its own weight, and a biasing unit that biases the transfer roll 40 toward the retracted position P0 side is particularly provided. I don't need it.

  6 to 10 are explanatory views showing the contact state of the photosensitive member 21 and the transfer roll 40, FIG. 6 is a plan view, and FIG. 7 is a view of the transfer roll 40 side as viewed from the photosensitive member 21 side. FIG. 8 is a perspective view, FIG. 9 is an explanatory view showing a power feeding mechanism 90 (torsion spring 91, lead-out wiring portion 92) used in the present embodiment, and FIG. 10 is a cross section at the position of the U groove portion 43a of the transfer casing 42. In both figures, (a) shows a state at the retracted position P0 where the transfer roll 40 has been retracted, and (b) shows a state at the contact position P1 where both contacted.

-When the photoconductor is stopped-
In these drawings, since the photosensitive member 21 is stopped at the retracted position P0 where the transfer roll 40 is retracted, the first helical gear 51 is also stopped. Therefore, the driving rotational force of the first helical gear 51 is not transmitted to the second helical gear 52, and the second helical gear 52 remains stopped without rotating. In this state, since the urging force of the coil spring 80 in the connection cylinder 61 of the support member 53 acts on the second helical gear 52 via the displacement member 70 of the displacement mechanism 54, The helical gear 52 is urged away from the transfer roll 40. The rotary shaft 52b of the second helical gear 52 is held by the bearing portion 37 of the holding arm 35 of the photoreceptor housing 34 so as to be rotatable and slidable along the axial direction. Since the movement of the second helical gear 52 in the direction away from the transfer roll 40 is restricted when the gear body 52a of the helical gear 52 abuts against the end of the bearing portion 37, the second helical gear 52 is restricted. The gear 52 is stopped at a predetermined stop position (corresponding to the initial position P0).

  At this time, many rods 71 of the displacement member 70 protrude from the connection cylinder 61 of the support member 53, but the stopper projection 73 is caught at the opening end of the long hole 62 of the connection cylinder 61, and the rod 71 is There is no concern of slipping out of the connecting cylinder 61, and the return amount of the second helical gear 52 is regulated. Further, since the push-up arm 75 of the displacement member 70 is disposed at a position where it does not contact the abutting wall 78 of the holding arm 35, the displacement member 70 displaces the support member 53 toward the contact position P1 side of the transfer roll 40. However, the bearing 44 integrated with the support member 53 is held at the position as it is, and the transfer roll 40 is held at the retracted position P0.

-Photoconductor drive rotation-
Next, when the photosensitive member 21 is driven and starts rotating, the second helical gear 52 meshed with the first helical gear 51 is rotated by the rotation of the first helical gear 51, The second helical gear 52 receives a thrust force in a direction toward the end side of the transfer roll 40. As a result, the second helical gear 52 moves toward the end of the transfer roll 40 against the urging force of the coil spring 80 built in the connection cylinder 61 of the support member 53, The rod 61 of the displacement member 70 that comes into contact with the overhanging portion 52 d of the helical gear 52 is integrally moved toward the end side of the transfer roll 40. Then, the tip of the push-up arm 75 of the displacement member 70 comes into contact with the corner portion 78a of the abutment wall 78, and the push-up arm 75 is inclined by the inclined surface 77 of the push-up portion 76 provided at the tip of the push-up arm 75. Gradually moves toward the top of the butting wall 78 and rides on the top of the butting wall 78. In this state, the movement of the push-up arm 75 of the displacement member 70 causes the entire displacement member 70 to move in a direction approaching the peripheral surface of the photoconductor 21, and thus the support member to which the rod 71 of the displacement member 70 is connected. The connection cylinder 61 of 53 is lifted in the direction approaching the peripheral surface of the photosensitive member 21, and the bearing 44 integrated with the connection cylinder 61 extends along the U groove 43 a of the bearing holding portion 43 of the transfer housing 42. It moves in a direction approaching the peripheral surface of the photoreceptor 21. For this reason, the transfer roll 40 approaches the photosensitive member 21 side together with the bearings 44 and finally reaches a contact position P <b> 1 where it contacts the photosensitive member 21. Here, in the present embodiment, regarding the push-up portion 76 of the push-up arm 75 of the displacement member 70, the displacement amount along the contact / separation direction of the transfer roll 40 is the difference between the contact position P1 of the transfer roll 40 and the retracted position P0. It is set slightly larger than the distance between them, and the transfer roll 40 is disposed in pressure contact with the photosensitive member 21 at the contact position P1.

  Further, since the photosensitive member 21 continues to rotate at the contact position P1, the first helical gear 51 and the second helical gear 52 continue to rotate, and the second helical gear 52 has a thrust force. Continue to work. However, since the amount of movement of the rod 71 in the sliding direction is restricted at the position where the flange portion 72 of the rod 71 of the displacement member 70 abuts against the end of the connection cylinder 61 of the support member 53, the second helical gear. The amount of movement of 52 in the thrust direction is regulated by the movement restriction of the rod 71 of the displacement member 70. For this reason, the second helical gear 52 cannot move further to the transfer roll 40 side. Thereby, the axial position of the transfer roll 40 is maintained at the contact position P1.

-When stopped after rotation of photosensitive member drive-
Next, when the photosensitive member 21 is stopped, the first helical gear 51 is stopped, so that no thrust force is generated in the second helical gear 52. Then, the urging force of the coil spring 80 exerts an effect and tries to move the second helical gear 52 away from the transfer roll 25 via the rod 71 of the displacement member 70. As a result, the second helical gear 52 gradually moves away from the transfer roll 40 while rotating along the teeth of the first helical gear 51 being stopped. Similarly, since the entire displacement member 70 moves together, the push-up arm 75 of the displacement member 70 moves away from the abutment wall 78. As a result, when the push-up portion 76 of the push-up arm 75 is detached from the abutting wall 78, the push-up operation of the support member 53 by the push-up arm 75 is released, so that the transfer roll 40 is moved by its own weight. Both the bearings 44 are retracted to the retracted position P0 away from the peripheral surface of the photoreceptor 21. Thereafter, the transfer roll 40 repeats contact and separation between the retracted position P0 and the contact position P1 as the photoconductor 21 rotates and stops.

As described above, in the present embodiment, when the transfer roller 40 is brought into contact with or separated from the photosensitive member 21, the contact / separation mechanism 50 using the rotational force that drives the photosensitive member 21 is used to rotate the photosensitive member 21. Since the transfer roll 40 is displaced to the contact position P1 where it contacts the photoconductor 21 and the photoconductor 21 stops, the transfer roll 40 is displaced to the retreat position P0 retracted from the photoconductor 21, so that another drive source is used. Therefore, an unnecessary contact state between the photoconductor 21 and the transfer roll 40 for a long time outside the image forming period can be avoided.
In the present embodiment, for example, the rotation of the photosensitive member 21 is continuously performed during a time when it is determined that image formation is performed in the image forming apparatus 10, and when it is determined that the image formation is finished. It goes without saying that the rotation of the photosensitive member 21 is not switched in a short time. It goes without saying that image formation is performed after a predetermined time has elapsed since the photosensitive member 21 starts to rotate, that is, after the transfer roll 40 is displaced to the contact position P1.

Further, in the present embodiment, as shown particularly in FIG. 8, the rotation center axes of the second helical gear 52 and the transfer roll 40 at the retracted position P0 are arranged on substantially the same line. Therefore, if the center positions of the connecting cylinder 61 of the support member 53 and the rod 71 of the displacement member 70 are set according to the rotation center axis of the transfer roll 40, the second helical gear 52 and the displacement member When the 70 rods 71 are brought into contact with each other, the center positions of the two can be substantially aligned to ensure a large contact area between the two, and the thrust force generated by the second helical gear 52 is easily transmitted to the displacement member 70. . In this example, the projecting portion 52d of the second helical gear 52 and the flange portion 72 formed at the end of the rod 71 of the displacement member 70 constitute a contact portion between them. Even if the displacement member 70 is displaced in the contact / separation direction of the transfer roll 40, the flange portion of the displacement member 70 that faces the protruding portion 52 d of the second helical gear 52 so that the contact area between the two can be maintained. It is preferable to select the area of 72 wider than the opposed area of the projecting portion 52d.
Further, the urging force of the coil spring 80 is also easily transmitted to the second helical gear 52 side. Therefore, in this example, it is easy to obtain a small and more stable contact / separation mechanism 50.

  In the present embodiment, the first helical gear 51 and the second helical gear 52 are provided on both ends of the photosensitive member 21 and the transfer roll 40, respectively. However, the first helical gear 51 and the second helical gear 52 are provided on one side. In this case, the second helical gear 52 moving direction and the moving direction of the displacement member 70 at the retracted position P0 are slightly displaced from each other on a straight line. Therefore, the transfer roll 40 is displaced between the retracted position P0 and the contact position P1 without any trouble. At this time, the posture angle of the push-up arm 75 of the displacement member 70 may be slightly changed.

In the present embodiment, the drum-shaped photosensitive member 21 is used as the rotating member. However, a belt member may be used as the rotating member. For example, a contact / separation mechanism between the photosensitive belt and the transfer roll 40 is acceptable. Alternatively, the above contact / separation mechanism may be used.
In the present embodiment, the transfer roll 40 can be stabilized at the retracted position P0 by its own weight. For example, an urging means for urging the transfer roll 40 toward the retracted position P0 is provided. Needless to say, you can.
Furthermore, in the present embodiment, an aspect in which the contact / separation mechanism 50 is used between the photoconductor 21 and the transfer roll 40 has been described. However, for example, an aspect in which a charging roll is used as a charger or a cleaning roll is used as a cleaner. In this case, when these are arranged on the lower side in the vertical direction with respect to the horizontal line passing through the center of the photosensitive member 21, the above-mentioned contact / separation mechanism may be used.

Embodiment 2
FIGS. 11A and 11B are explanatory views showing the main part of the transfer roll contacting / separating mechanism in Embodiment 2, and FIG. 11A shows the state when the transfer roll is disposed at the retracted position P0. (B) shows the state when the transfer roll is disposed at the contact position P1.
The contact / separation mechanism 50 of the transfer roll 40 used in the present embodiment is configured in substantially the same manner as in the first embodiment (see FIG. 5), but includes a displacement mechanism 54 different from the first embodiment. In particular, in the present embodiment, although the position of the transfer roll 40 is arranged closer to the lower side in the vertical direction with respect to the horizontal line passing through the center of the photoconductor 21, the transfer roll 40 is retracted from the contact position P1 to the retracted position P0. In addition, it is applied when the transfer roll 40 is difficult to return to the retracted position P0 only by its own weight action. In addition, the same code | symbol is attached | subjected to the component similar to Embodiment 1, and the description is abbreviate | omitted here.

In the present embodiment, the contact / separation mechanism 50 of the transfer roll 40 is configured by using substantially the same elements (first lotus not shown) as shown in FIGS. 11A, 11B and 12. A helical gear, a second helical gear 52, a support member 53 (a connecting cylinder 61, a long hole 62), and a coil spring 80 for returning the second helical gear 52 to the initial position are provided.
As shown in FIGS. 11 to 15, the displacement mechanism 54 includes a displacement member 70 (rod 71, flange 72, stopper projection 73, push-up arm 75, push-up portion 76, inclined surface 77 substantially the same as in the first embodiment. ) And an abutting wall 78 related to the pushing-up operation of the push-up arm 75. In addition, the transfer roll 40 positioned at the contact position P1 when the photosensitive member 21 is stopped is moved to the retracted position P0. A return mechanism 100 is provided for returning the support member 53 in a direction away from the peripheral surface of the photoreceptor 21 so as to be retracted.

In the present embodiment, the return mechanism 100 is provided with a pressing arm 101 that protrudes toward the end of the transfer roll 40 on a part of the holding arm 35 of the photoconductor casing 34, and the pressing arm 101 has a tip at the tip. A wedge-shaped pressing portion 102 is provided. The pressing unit 102 of this example has an inclined surface 103 that is inclined so as to approach the contact position P1 side of the transfer roll 40 toward selection.
In this example, the inclined surface 103 of the pressing portion 102 of the pressing arm 101 is an edge located closer to the lower half of the upper half of the flange 72 formed at the end of the rod 71 of the displacement member 70. A notch 110 is formed in the flange 72 facing the inclined surface 103 of the pressing part 102, and the notch 110 has substantially the same inclination as the inclined surface 103 of the pressing part 102. An inclined surface 111 is provided.
Here, since the bearing portion 37 and the push-down arm 101 of the second helical gear 52 are both provided on the holding arm 35 of the photosensitive member casing 34, the push-down arm 101 is the second helical gear 52. It is necessary to be disposed at a position that does not interfere with the gear 52. For this reason, in this example, as shown in FIG. 14, the rotation center axis of the second helical gear 52 is not arranged coaxially with the rotation center axis of the transfer roll 40, and is not aligned with the rotation center axis of the transfer roll 40. On the other hand, they are arranged non-coaxially deviating from the photosensitive member 21 side. The pressing arm 101 is provided on the side opposite to the side of the second helical gear 52 where the rotation center axis is located with respect to the rotation center axis of the transfer roll 40 as viewed from the photosensitive member 21 side. . In this example, the flange portion 72 of the displacement member 70 is provided with a dummy cutout portion 115 in addition to the cutout portion 110, which introduces the contact / separation mechanism 50 on both sides in the axial direction of the transfer roll 40. In order to use the same component as the displacement member 70 which is an element of the contact / separation mechanism 50, the notches 110 and 115 are provided at two locations.

Next, the behavior of the contact / separation mechanism of the transfer roll in the present embodiment will be described.
-Photoconductor drive rotation-
In this embodiment, when the photosensitive member 21 is driven and rotated, as shown in FIGS. 13 to 15, the first helical gear 51 and the second helical gear 52 are rotated, and the second helical gear 52 is rotated. A thrust force is generated in the gear 52, and the second helical gear 52 and the displacement member 70 move together to move toward the transfer roll 40. As a result, the push-up arm 75 of the displacement member 70 abuts against the abutting wall 78 of the holding arm 35 to perform the push-up action of the displacement member 7 and from the push-down portion 102 of the push-down arm 101 of the return mechanism 100. The notch part 110 formed in the collar part 72 of 70 is separated, and the return action by the return mechanism 100 is released.
During this time, since the return mechanism 100 is in the released state, the push-up arm 75 rides on the top of the abutting wall 78, and the entire position member 70 gradually approaches the peripheral surface of the photoreceptor 21. The transfer roll 40 comes into contact with the peripheral surface of the photoconductor 21 and reaches the contact position P1.

-Photoconductor drive rotation to stop-
On the other hand, when the photosensitive member 21 is stopped, the displacement member 70 and the second helical gear 52 are gradually moved away from the transfer roll 40 by the biasing force of the coil spring 80. As a result, when the push-up arm 75 of the displacement member 70 comes off the top of the abutting wall 78 of the holding arm 35, the transfer roll 40 is separated from the peripheral surface of the photoreceptor 21. At this time, as the displacement member 70 moves, the flange 72 of the displacement member 70 also moves away from the end of the transfer roll 40. Then, the notch portion 110 formed in the flange portion 72 of the displacement member 70 abuts on the pressing portion 102 of the pressing arm 101 of the return mechanism 100, and the displacement member 70 moves further in the direction away from the end portion of the transfer roll 40. Then, since the inclined surface 111 of the notch 110 is pushed down along the inclined surface 103 of the pressing portion 102, the displacement member 70 moves in a direction away from the peripheral surface of the photoreceptor 21. When the second helical gear 52 returns to the initial position, the movement of the displacement member 70 also stops, and the return mechanism 100 restrains the displacement member 70 at a predetermined position away from the peripheral surface of the photoconductor 21. In this state, the bearing 44 supported by the displacement member 70 via the support member 53 also moves away from the peripheral surface of the photosensitive member 21 following the movement of the displacement member 70, and as a result, as a result, the transfer roll 40. Is held at the retracted position P0. In this embodiment, when the photosensitive member 21 is stopped, even if it is difficult to reach the retreat position P0 only by the self-weight action of the transfer roll 40, in this embodiment, the transfer roll 40 is forcibly retracted by the return mechanism 100. It is possible to return to the position P0.

Here, the timing at which the push-up arm 75 of the displacement member 70 comes off from the abutment wall 78 of the holding arm 35 is the same as the timing at which the push-down portion 102 of the push-down arm 101 of the return mechanism 100 hits the notch 110 of the displacement member 70. Such timing may be used, or different timing may be used.
In this embodiment, as shown in FIGS. 14A and 14B, the rotation center of the second helical gear 52 with respect to the rotation center axis of the transfer roll 40 when viewed from the photosensitive member 21 side. The shaft is biased. Therefore, regarding the contact portion structure between the second helical gear 52 and the displacement member 70, the amount of displacement in the contact / separation direction of the transfer roll 40 is taken into consideration, and the protruding portion 52d of the second helical gear 52 It is preferable to select such that a contact area with the flange portion 72 of the displacement member 70 can be secured.

  In such a configuration, the return mechanism 100 is in a state where the pressing portion 102 of the pressing arm 100 hits the notch portion 110 of the displacement member 70 and restrains the position of the displacement member 70 at the retracted position P0. Therefore, if the return member 100 is used to restrain and hold the displacement member 70, the transfer roll 40 is restrained and held at the retracted position P0 even if a mechanical impact is applied during transportation of the image forming apparatus 10, for example. Therefore, the transfer roll 40 does not flutter.

Embodiment 3
FIG. 16 is an explanatory view showing an outline of the image forming apparatus according to the third embodiment, and FIGS. 17A and 17B show a contact / separation mechanism between the photoconductor 21 and the transfer roll 25 according to the present embodiment. It is explanatory drawing, (a) has shown the state in the retracted position P0 which both separated, and (b) has shown the state in the contact position P1 which both contacted. In these drawings, the contact / separation mechanism of the present embodiment is configured in substantially the same manner as in the second embodiment, but unlike the second embodiment, the transfer roll 40 is in relation to a horizontal line passing through the center of the photoreceptor 21. It is arranged on the upper side in the vertical direction. In addition, the same code | symbol is attached | subjected to the component similar to Embodiment 2, and the description is abbreviate | omitted here.

  In the present embodiment, as shown in FIG. 16, the center position of the transfer roll 40 is disposed above the center position of the photoconductor 21. Therefore, for example, as in the first embodiment (see FIG. 6), in the aspect in which the second helical gear 52 and the displacement member 70 of the displacement mechanism 54 are merely in surface contact, the transfer roll 40 has its own weight. There is a possibility that the object at the retracted position P0 may reach the contact position P1. As such a countermeasure, for example, a separate urging unit may be provided for the transfer roll 40 so as to be maintained at the retracted position P0 separated from the photosensitive member 21, but such a urging unit is a transfer unit. Since an urging force against the gravity of the roll 40 is required, it is not easy to displace the transfer roll 40 between the retracted position P0 and the contact position P1 in such an aspect having the urging force.

  In the present embodiment, a configuration is employed in which the transfer roll 40 can be stably held at the retracted position P0 without the biasing means for biasing the transfer roll 40 to be kept at the retracted position P0. It is a thing. Therefore, the present embodiment is realized with the same configuration as that of the second embodiment, but the relationship between the push-up arm 75 and the abutment wall 78 of the displacement member 70 and the notch of the displacement member 70 as the return mechanism 100 are provided. The relationship between the part 110 and the pressing part 102 of the pressing arm 101 is noted.

  In other words, in the present embodiment, the transfer roll 40 at the retracted position P 0 is kept in a state where the pressing portion 102 of the pressing arm 101 hits the notch portion 110 of the displacement member 70 and is separated from the photoconductor 21. Therefore, when the photosensitive member 21 rotates, the second helical gear 52 moves to the transfer roll 40 side by the thrust force generated in the second helical gear 52 that meshes with the first helical gear 51. start. Then, with the movement of the displacement member 70, the cutout portion 100 of the displacement member 70 comes out of the push-down portion 102 of the push-down arm 101, while the push-up portion 76 of the push-up arm 75 of the displacement member 70 is brought into contact with the abutting piece wall 78. Move in the direction to hit.

  Here, if the push-up arm 75 of the displacement member 70 first hits the abutment wall 78 and tries to enter between the abutment wall 78 and the bearing 44, the push-down arm 101 of the return mechanism 100 is pushed down. In a state where the cutout portion 110 of the displacement member 70 is not removed from the portion 102, an extra load is applied to the displacement member 70 and the like, and for example, the displacement member 70 may be damaged. Therefore, under the condition that the notch portion 110 of the displacement member 70 is removed from the pressing portion 102 of the pressing arm 101, the push-up portion 76 of the lifting arm 75 hits the abutting wall 78, and the lifting arm 75 hits the abutting wall 78. Just ride on. In particular, by matching the timings of both, the transfer roll 40 can be brought into contact with the photosensitive member 21 by a relaxation operation. As a result, the transfer roll 40 reaches the contact position P1.

  Next, when the photosensitive member 21 is stopped, the second helical gear 52 and the displacement member 70 are moved away from the transfer roll 40 by the biasing force of the coil spring 80, and the push-up arm 75 of the displacement member 70 is pushed. When the notch 110 of the displacement member 70 comes off from the abutting wall 78 and hits the pressing part 102 of the pressing arm 101 of the return mechanism 100, the notch 110 of the displacement member 70 is pushed down along the inclined surface 103 of the pressing part 102. The displacement member 70 is displaced in a direction away from the photoconductor 21. As a result, the transfer roll 40 reaches the retracted position P <b> 0 separated from the photoconductor 21.

  In the present embodiment, when the photosensitive member 21 is driven to rotate, the timing at which the push-up arm 75 of the displacement member 70 rides on the abutting wall 78 and the notch portion of the displacement member 70 from the push-down portion 102 of the push-down arm 101 of the return mechanism 100. The timing at which 110 is removed is adjusted, but the timing at which the notch 110 of the displacement member 70 is removed from the pressing portion 102 of the pressing arm 101 is earlier than the timing at which the push-up arm 75 of the displacement member 70 rides on the abutting wall 78. By doing so, damage to the displacement member 70 is effectively avoided. In this case, however, it goes without saying that the transfer roll 40 comes into contact with the photosensitive member 21 with a certain degree of impact force when reaching the contact position P1 from the retracted position P0.

  In this embodiment, the transfer roll 40 is brought into contact with and separated from the photoreceptor 21. However, the present invention is not limited to this, and instead of the transfer roll 40, a charging roll as a charging device and a cleaning device are used. You may make it use for a cleaning roll.

  DESCRIPTION OF SYMBOLS 1 ... Rotating body, 2 ... Movable member, 3 ... 1st drive transmission member, 4 ... 2nd drive transmission member, 5 ... Support member, 6 ... Displacement mechanism, 6a ... Pushing part, 7 ... Axial direction movable part, 8 ... movable part in contact / separation direction, 9 ... displacement member, P0 ... retracted position, P1 ... contact position

Claims (12)

A contact / separation mechanism for contacting / separating the movable member with respect to the circumferential surface of the rotating body capable of driving rotation,
A first drive transmission member provided on a width direction end portion crossing the rotation direction of the rotating body, the rotation force of the rotating body being transmitted, and driven to rotate around the rotation center;
It is provided so as to relate to the first drive transmission member, and is held at a predetermined initial position when the rotating body does not rotate by rotation, and the first drive transmission member rotates when the rotating body rotates by driving. A second drive transmission member that transmits force and rotates following the center of rotation, and is moved toward the rotating body along the rotation axis direction;
A support member that supports the movable member so as to be able to contact and separate between a contact position where the movable member contacts the peripheral surface of the rotating body and a retracted position where the movable member retracts;
Provided between the second drive transmission member and the support member, and when the second drive transmission member is moved from the initial position along the direction of the rotation center axis, A displacement mechanism for pressing the support member in a direction approaching the peripheral surface of the rotating body and displacing the movable member to the contact position;
An approach / separation mechanism characterized by comprising: The contact / separation mechanism according to claim 1,
The first drive transmission member, the second drive transmission member, the support member, and the displacement mechanism are respectively provided on both ends in the width direction intersecting the rotation direction of the rotating body. Contact / separation mechanism. The contact / separation mechanism according to claim 1 or 2,
The contact / separation mechanism, wherein the first drive transmission member and the second drive transmission member are constituted by helical gears that mesh with each other. The contact / separation mechanism according to claim 1 or 2,
The contact / separation mechanism, wherein the second drive transmission member includes an urging member that is urged so as to be held at the initial position when the rotating body is not driven to rotate. The contact / separation mechanism according to claim 4,
The contacting / separating mechanism, wherein the urging member is accommodated in the support member. The contact / separation mechanism according to claim 1 or 2,
The displacement mechanism is provided separately from or integrally with the second drive transmission member, and along with the second drive transmission member, along the rotation center axis direction of the second drive transmission member, on the support member side An axially movable part that moves to and an approaching / separating direction movable part that moves the movable member from the retracted position to the contact position via the support member as the axially movable part moves.
The contact / separation mechanism having a pressing portion that presses the support member in a direction approaching the peripheral surface of the rotating body at at least one position of the axial direction movable portion or the contact / separation direction movable portion. The contacting / separating mechanism according to claim 6,
The displacement mechanism has one displacement member in which the axially movable portion and the contact / separation direction movable portion are integrated, and guides the axially movable portion while sliding with respect to the support member, A contact / separation mechanism, wherein the support member is pressed toward a contact position of the movable member by a pressing portion provided in the movable portion in the contact / separation direction. The contacting / separating mechanism according to claim 6,
The displacement mechanism includes the axially movable portion and the contact / separation direction movable portion as separate bodies, and the pressing mechanism is provided at a portion where the axial direction movable portion and the contact / separation direction movable portion are engaged. A characteristic contact and separation mechanism. The contact / separation mechanism according to claim 1 or 2,
The displacement mechanism includes a return mechanism that returns the support member to the retracted position side of the movable member when the second drive transmission member returns to the initial position. The contact / separation mechanism according to claim 9,
The return mechanism of the displacement mechanism is arranged in parallel at a position substantially parallel to the rotation center axis of the second drive transmission member,
When the second drive transmission member returns to the initial position, the rotation center axis of the second drive transmission member is the center of the movable member in the direction along the width direction of the rotary body when viewed from the photosensitive member side. A contact / separation mechanism characterized in that the contact / separation mechanism is arranged to be offset with respect to the shaft. In the contact and separation mechanism according to any one of claims 1 to 10, the movable member is a rotatable rotating member.
The contacting / separating mechanism, wherein the support member is provided on a bearing that rotatably holds the movable member as a rotating member. A latent image holding body for holding an electrostatic latent image;
A charger that charges the latent image carrier to form an electrostatic latent image;
A developing device for developing the electrostatic latent image on the latent image holding member with a developer;
A transfer device for transferring an image developed by the developing device and formed on the latent image holding member to a recording material;
A cleaning device for cleaning the latent image holding member after being transferred by the transfer device;
Including
12. The contact / separation mechanism between the latent image holding member and a rotating member when the latent image holding member is a rotating member and at least one of the charger, the transfer unit, and the cleaning unit is a movable member. An image forming apparatus using a contact / separation mechanism.

Images