JP2014227264A - Carrier device and image formation apparatus using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To carry a recording material stably by reducing the difference in holding pressure on both sides in the width directions intersecting the carrying direction, in a sandwiched state by using a pair of rotation members.SOLUTION: A carrier device includes a carrier member 3 which is rotatable, faces an image holding body 1 as a rotatable opposite member, holds a recording material S between it and the image holding body 1 as the opposite member, and carries the recording material S, and a holding mechanism 4 which holds both ends of the carrier member 3 and presses the carrier member 3 toward the image holding body 1 as the opposite member. The holding mechanism 4 includes a pair of holding members 5 which hold rotatably both end support shafts 3s of the carrier member 3, a rotation shaft 6 which supports rotatably the holding members 5, a connection member 7 which extends in the same direction as the axial direction of the carrier member 3 and connects the holding members 5 together at positions of the holding members 5 separated from the rotation shaft 6 and the support shaft 3s of the carrier member 3, and a tension member 8 which pulls a central part, in the longitudinal direction, of the connection member 7 so that the carrier member 3 is pressed toward the image holding body 1 as the opposite member.

Description

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

Conventionally, as this type of image forming apparatus, for example, the one described in Patent Document 1 is already known.
Patent Document 1 includes a supporting member that supports the shafts at both ends of the transfer member with a single member, and a pressing member that presses about the center of the supporting member in a direction in which the transfer member is pressed against the image carrier. An image forming apparatus having the same is disclosed.

Japanese Patent Laid-Open No. 7-134506 (Example, FIG. 1)

  The technical problem to be solved by the present invention is to reduce the holding pressure difference on both sides in the width direction intersecting the recording material conveyance direction when the recording material is nipped and conveyed using the pair of rotating members. An object of the present invention is to provide a conveying apparatus that stably conveys a recording material and an image forming apparatus using the conveying apparatus.

  According to a first aspect of the present invention, there is provided a rotatable conveying member that opposes a rotatable opposing member and conveys the recording material with the opposing member sandwiched between the rotating member and the opposite member. A holding mechanism that pressurizes the conveying member, and the holding mechanism rotatably supports a pair of holding members on both ends of the conveying member, and a rotating shaft that rotatably supports the holding member. And a connecting member that extends in the same direction as the axial direction of the transport member and connects the holding members at a portion of the holding member that is away from the rotating shaft and the support shaft of the transport member, and the transport member And a tension member that pulls a central portion in the length direction of the connecting member so as to be pressurized toward the opposing member.

According to a second aspect of the present invention, in the transport device according to the first aspect, the tension member is pulled in a direction substantially orthogonal to a reference line connecting a rotation shaft of the holding member and an action point of the tension member. It is the conveying apparatus characterized by this.
According to a third aspect of the present invention, in the transport device according to the first or second aspect, the holding member has the apex of the rotating shaft, the support shaft holding portion of the transport member, and the action point portion of the tension member. It is a conveying device characterized by being formed in a substantially triangular shape arranged in the vicinity.
According to a fourth aspect of the present invention, in the conveyance device according to any one of the first to third aspects, the central axis connecting the rotation shaft of the holding member and the support shaft of the conveyance member is the rotation axis of the holding member and the tension. It is a conveying apparatus characterized by being arrange | positioned at substantially right angle with respect to the reference line which connects the action point part of a member.
The invention according to claim 5 is the transport apparatus according to any one of claims 1 to 3, wherein the holding member is transported to the opposing member in a direction substantially orthogonal to the direction in which the tensile force is applied by the tension member. A conveying device that pressurizes a member.

According to a sixth aspect of the present invention, in the conveying device according to any of the first to fifth aspects, the tensile force exerted by the tension member on the holding member so as to hold the pressurized state of the conveying member against the opposing member. It is a conveying apparatus provided with the pressurization holding mechanism which provides.
The invention according to claim 7 is the conveyance device according to claim 6, wherein the pressure holding mechanism pulls the holding member with the tension member so as to release the pressure state of the conveyance member with respect to the facing member. A conveying device comprising a pressure release unit that reduces a force application state.
The invention according to claim 8 is the conveyance device according to claim 7, wherein the pressurizing and holding mechanism moves a movable member to apply or reduce a tensile force by the tension member, and advances and retracts the movable member. A transport apparatus comprising an advance / retreat mechanism and an operation member for operating the advance / retreat mechanism.

The invention according to claim 9 includes an image holding member as an opposing member that forms and holds an image, and a conveying device that conveys a recording material so as to pass through an image transfer area of the image holding member, An image forming apparatus using the conveyance device according to any one of claims 1 to 8 as the conveyance device.
According to a tenth aspect of the present invention, in the image forming apparatus according to the ninth aspect, the conveying member of the conveying device faces an image carrier as a rotatable counter member, and a recording material is placed between the image carrier and the image carrier. An image forming apparatus characterized by being a transfer member that sandwiches and conveys and transfers an image formed on an image carrier to a recording material.
According to an eleventh aspect of the present invention, in the aspect of the image forming apparatus according to the tenth aspect having a plurality of image holding members, the holding mechanism of the conveying device is provided corresponding to each image holding member, and each holding mechanism is provided. Is a common pressurization that applies or reduces a tensile force by each of the tension members to the holding member so as to hold or release the pressure state of the transfer member as each of the conveying members with respect to each of the image holding bodies. An image forming apparatus including a holding mechanism.
According to a twelfth aspect of the present invention, in the image forming apparatus according to the eleventh aspect, in the aspect having the paired common support housings on both sides in the axial direction of the conveying member held by the holding mechanisms, the holding mechanisms The image forming apparatus is characterized in that a rotation shaft of each holding member is supported by the common support housing.
According to a thirteenth aspect of the present invention, in the image forming apparatus according to the eleventh aspect, the pressurizing and holding mechanism includes a hooked portion that is hooked by a tensile member of each holding mechanism, and applies a tensile force by each tensile member. Alternatively, the image forming apparatus includes one movable member movably provided for reduction, an advance / retreat mechanism for moving the movable member back and forth, and an operation member for operating the advance / retreat mechanism.
According to a fourteenth aspect of the present invention, in the image forming apparatus according to the twelfth aspect, the common support housing of the pair configuration is between two adjacent support positions among the support positions of the rotation shafts of the holding members and An image forming apparatus comprising one or a plurality of reinforcing members positioned at positions apart from a straight line connecting the two support positions and spanned in a state of being connected to each other.

According to the first aspect of the present invention, when the recording material is nipped and conveyed using the pair of rotating members, the difference in nipping pressure between both sides in the width direction intersecting with the conveying direction of the recording material is reduced. Can be stably conveyed.
According to the invention which concerns on Claim 2, the rotational moment with respect to the rotating shaft of a holding member can be provided efficiently, and a conveyance member can be pressurized to an opposing member.
According to the third aspect of the present invention, the holding member is deformed without unnecessarily increasing the rigidity of the holding member when pressurizing the conveying member against the opposing member as compared with the aspect without this configuration. Can be suppressed.
According to the invention which concerns on Claim 4, the conveyance member is efficiently pressurized with respect to an opposing member by making the tensile force by a tension member act toward the direction along the contact area of an opposing member and a conveyance member. be able to.
According to the invention which concerns on Claim 5, the rotational moment based on the tensile force by a tension member can be transmitted without waste, and a conveyance member can be pressurized efficiently with respect to an opposing member.
According to the invention which concerns on Claim 6, compared with the aspect which does not have this structure, the pressurization state of an opposing member and a conveyance member can be kept favorable.
According to the invention which concerns on Claim 7, compared with the aspect which does not have this structure, the pressurization state of an opposing member and a conveyance member can be cancelled | released as needed.
According to the invention which concerns on Claim 8, when hold | maintaining and canceling | releases the pressurization state of a conveyance member with respect to an opposing member, a pressurization holding mechanism can be constructed | assembled easily.
According to the ninth aspect of the present invention, when the recording material is conveyed to the image transfer area of the image carrier, the sandwiching pressure difference between both sides in the width direction intersecting the conveying direction of the recording material is reduced, and the recording material is stably provided. Can be transported.
According to the tenth aspect of the present invention, when the recording material is nipped and conveyed with the image carrier, the difference in nipping pressure on both sides in the width direction intersecting the conveying direction of the recording material is reduced, and the transfer property is good. The recording material can be stably conveyed while maintaining the above.
According to the eleventh aspect of the present invention, in the image forming apparatus having a plurality of image holding members, the transfer member as the conveying member is efficiently pressed against the plurality of image holding members, and the pressing state can be easily set. It can be canceled.
According to the twelfth aspect of the present invention, in an image forming apparatus having a plurality of image holding members, the positional accuracy of each holding mechanism can be kept good, and the pressure state of the conveying member against the opposing member can be kept as desired. it can.
According to the thirteenth aspect of the present invention, in an image forming apparatus having a plurality of image carriers, a transfer member as a conveying member is efficiently pressed against the plurality of image carriers by a simple operation. The pressure state can be easily released.
According to the invention of claim 14, in the aspect in which the transfer members as the plurality of transport members are held by the plurality of holding mechanisms, the supporting strength for the plurality of holding mechanisms is increased without unnecessarily increasing the rigidity of the support housing. It can be secured sufficiently.

(A) is explanatory drawing which shows the outline | summary of embodiment of the image forming apparatus containing the conveying apparatus to which this invention was applied, (b) is explanatory drawing which shows the structural example of the conveying apparatus shown by (a), (c) ) Is an explanatory diagram viewed from the direction C in (b). 1 is an explanatory diagram illustrating an overall configuration of an image forming apparatus according to a first embodiment. FIG. 3 is a perspective explanatory view of the periphery of a transfer unit of the image forming apparatus shown in FIG. 2 as viewed obliquely from above. FIG. 4 is an explanatory diagram illustrating a state in which a recording material guide member is removed from the perspective explanatory diagram of the image forming apparatus in FIG. 3. (A) is explanatory drawing which shows an example of the holding mechanism of each transfer roll, (b) is an arrow line view seen from the BB line direction in (a). It is an example of a holding mechanism and a pressure holding mechanism of each transfer roll, and is an explanatory view showing an operation state in which the pressure state of each transfer roll against each photoconductor is held by the pressure holding mechanism. FIG. 6 is an explanatory diagram illustrating an operation state in which a pressure state of each transfer roll with respect to each photoconductor is released by the pressure holding mechanism, which is an example of a holding mechanism and a pressure holding mechanism of each transfer roll. FIG. 3 is an explanatory diagram showing a layout of a transfer roll used in Embodiment 1 and a layout of each part of a holding mechanism. (A) is explanatory drawing which shows the operation principle at the time of hold | maintaining the pressurization state of the transfer roll by a pressurization holding mechanism, (b) is the operation principle at the time of canceling | releases the pressurization state of the transfer roll by a pressurization holding mechanism. It is explanatory drawing shown. (A) is explanatory drawing which shows the operation principle of the holding mechanism at the time of hold | maintaining the pressurization state of the transfer roll by a pressurization holding mechanism, (b) is at the time of canceling | releases the pressurization state of the transfer roll by a pressurization holding mechanism. It is explanatory drawing which shows the operation principle of a holding mechanism. (A) is explanatory drawing which shows an example of the holding mechanism of the transfer roll in the comparative form 1, (b) is explanatory drawing which shows an example of the holding mechanism of the transfer roll in the comparative form 2, (c) is in (b) It is arrow explanatory drawing seen from C direction. FIG. 10 is an explanatory diagram illustrating a configuration example of a transport device used in an image forming apparatus according to a second embodiment.

Outline of Embodiment FIG. 1A is an explanatory diagram showing an outline of an embodiment of an image forming apparatus to which the present invention is applied.
In FIG. 1, an image forming apparatus includes an image carrier 1 (1a to 1d in this example) as an opposing member that forms and holds an image, and a recording material so as to pass through an image transfer area of the image carrier 1. And a transport device 2 for transporting S.
In this example, as shown in FIG. 1B, the conveying device 2 is opposed to the image holding body 1 as a rotatable opposing member, and between the image holding body 1 (1a to 1d) as the opposing member. A rotatable transport member 3 (3a to 3d in this example) that sandwiches and transports the recording material S, and both ends of the transport member 3 are held, and the transport member 3 is attached to the image carrier 1 as an opposing member. A holding mechanism 4 that pressurizes the holding mechanism 4. The holding mechanism 4 includes a pair of holding members 5 that rotatably support the both end support shafts 3s of the transport member 3, and a rotating shaft 6 that rotatably supports the holding member 5. A connecting member 7 that extends in the same direction as the axial direction of the conveying member 3 and connects the holding members 5 at a portion of the holding member 5 away from the rotating shaft 6 and the support shaft 3s of the conveying member 3; In the length direction of the connecting member 7 so that the pressure is pressed toward the image carrier 1 as the opposing member. A tension member 8 pulling the central portion, and a.

In such technical means, the facing member 1 includes a wide range of functional members other than the conveying member and opposed to the conveying member 3 as well as a functional member as the conveying member.
In the embodiment shown in FIG. 1, the image holding member 1 is used as the facing member, and the conveying member 3 faces the image holding member 1 as a rotatable facing member, and the recording material is interposed between the image holding member 1 and the image holding member 1. A transfer member is used that transports the image while holding S therebetween and transferring the image formed on the image carrier 1 to the recording material S.
Further, the pair of holding members 5 only need to hold both end support shafts 3 s of the conveying member 3 so as to be rotatable, and these holding members 5 are supported so as to be rotatable around the rotating shaft 6. That's fine.
Furthermore, the connecting member 7 may be any member that connects the pair of holding members 5, but it is necessary to provide the connecting member 7 at a site away from the rotating shaft 6 and the support shaft 3 s of the conveying member 3. If the connecting member 7 is stretched over the same part as the rotating shaft 6 and the support shaft 3s of the conveying member 3, the conveying member 3 is pressed against the image carrier 1 as the opposing member by the tensile force of the tensile member 8. It is difficult.
Furthermore, the central portion of the connecting member 7 in the length direction means a portion of the connecting member 7 corresponding to the center in the axial direction of the conveying member 3, but not only the central position of the connecting member 7 in the length direction. In consideration of the mounting tolerance of the hook portion of the tension member 8, a wide range includes at least a part of the hook portion of the tension member 8 disposed at the center of the connecting member 7.
On the other hand, in the pressing method using the pressing member, the seating surface at the point of action of the pressing member is unstable, and there is buckling due to the compression deformation of the pressing member, so the pressing direction and the applied pressure vary. . In this respect, the tension method using the tension member 8 is more stable in the pressing direction and pressure than the pressing method using the pressing member.

Next, a typical aspect or a preferable aspect of each component will be described.
First, as a preferable aspect of the tension member 8, an aspect in which the tension member 8 is pulled in a direction substantially orthogonal to a reference line connecting the rotation shaft 6 of the holding member 5 and the action point of the tension member 8 can be cited. This aspect is preferable in that a rotation moment can be efficiently applied around the rotation axis 6 of the holding member 5.
Moreover, as a preferable aspect of the holding member 5, it is formed in the substantially triangular shape by which the rotating shaft 6, the spindle holding part of the conveyance member 3, and the action point part of the tension member 8 are each arrange | positioned in the vertex vicinity. An embodiment is mentioned. In this embodiment, the shape of the holding member 5 may be selected as appropriate, but it is possible to increase the bending rigidity compared to the substantially L shape by making the shape substantially triangular.
Furthermore, as another preferable aspect of the holding member 5, the central axis connecting the rotation shaft 6 of the holding member 5 and the support shaft 3 s of the conveying member 3 is the point of action of the rotation shaft 6 of the holding member 5 and the tension member 8. The aspect arrange | positioned at substantially right angle with respect to the reference line which ties. In this aspect, regarding the positional relationship between the rotary shaft 6, the support shaft holding portion of the transport member 3, and the action point of the tension member 8, the support shaft holding portion of the transport member 3 and the action point of the tension member 8 are respectively The mode selected at a distant position is preferable in that the rotational moment due to the tensile force is easily transmitted to the support shaft holding portion of the transport member 3.
Furthermore, as another preferred embodiment of the holding member 5, there is one in which the conveying member 3 is pressed against the image holding body 1 as an opposing member in a direction substantially orthogonal to the direction of the tensile force applied by the tension member 8. It is done. In this aspect, the direction in which the tensile force is applied by the tension member 8 is arbitrary, but as long as the direction is substantially perpendicular to the pressurizing direction of the conveying member 3 with respect to the image carrier 1 as the opposing member, compared to the other directions. The pressurizing effect is preferable.

Further, as a preferable aspect of the conveying device 2, pressurization that applies a tensile force by the tension member 8 to the holding member 5 so as to hold the pressurized state of the conveying member 3 with respect to the image holding body 1 as an opposing member. The aspect provided with the holding mechanism 10 is mentioned. Here, as shown in FIG. 1C, the pressure holding mechanism 10 applies a predetermined tensile force Ft to the holding member 5, and applies a pressure Fp of the conveying member 3 to the image holding body 1 as an opposing member. Can be appropriately selected as long as the value is kept substantially constant.
Further, as a preferable aspect of the pressure holding mechanism 10, the tension applied by the tension member 8 to the holding member 5 is reduced so that the pressure state of the conveying member 3 with respect to the image holding body 1 as the opposing member is released. The aspect which comprises the pressure release part to perform is mentioned. Here, to reduce the application state of the tensile force is not to cause the tensile force to act, but it is only necessary that the tensile force is at least smaller than that at the time of action.
Furthermore, as a typical aspect of the pressure holding mechanism 10, a movable member that can be moved to apply or reduce the tensile force by the tension member 8, an advance / retreat mechanism that moves the movable member back and forth, and an operation of the advance / retreat mechanism And an operation member. Here, as the advance / retreat mechanism, any mechanism may be used as long as the movable member is advanced / retracted. Typically, a mechanism using an eccentric cam is used, and the advance / retreat locus is not limited to a straight line but may be a curved line. Further, the operation member may be any member that gives necessary movement to the advance / retreat mechanism. For example, if an eccentric cam mechanism is used as the advance / retreat mechanism, an operation member (such as a handle) capable of rotating operation may be used.

As a preferable aspect of the image forming apparatus having a plurality of image holding bodies 1, the holding mechanism 4 of the transport device 2 is provided corresponding to each image holding body 1, and each holding mechanism 4 is connected to each image holding body. 1 is provided with a common pressure holding mechanism 10 that applies or reduces the tensile force of each tension member 8 to the holding member 5 so as to hold or release the pressure state of the transfer member as each conveyance member 3 with respect to 1. The aspect which is mentioned is mentioned. In this aspect, each image holding body 1 is provided with a holding mechanism 4, and the pressure holding mechanism 10 common to each holding mechanism 4 is provided.
And as a typical support structure of the aspect which has the some holding mechanism 4, each holding | maintenance in the aspect which has the common support housing | casing of a pair structure on the axial direction both sides of the conveyance member 3 hold | maintained at each holding mechanism 4 An example of the mechanism 4 is one in which the rotation shaft 6 of each holding member 5 is supported on a common support housing. In this example, since each holding mechanism 4 is supported by a common support housing, the bearing portion on which the rotation shaft 6 of each holding member 5 is supported is placed at a predetermined position with respect to the common support housing. If formed, the positional relationship between the holding mechanisms 4 can be determined with high accuracy.
Further, as a typical aspect of the common pressure holding mechanism 10, each of the holding members 4 to be hooked on the tension member 8 of each holding mechanism 4 is provided and moved to apply or reduce the tensile force by each tension member 8. The aspect which has one movable member provided so that it can move, the advancing / retreating mechanism which moves this movable member back and forth, and the operation member which operates this advancing / retreating mechanism is mentioned.
Furthermore, as a preferable support structure of the aspect having a plurality of holding mechanisms 4, the common support housing of the pair configuration is between two adjacent support positions among the support positions of the rotating shaft 6 of each holding member 5 and An embodiment having one or a plurality of reinforcing members that are positioned at positions away from a straight line connecting the two support positions and are connected to each other is provided. In this aspect, each holding mechanism 4 and the pressure holding mechanism 10 are configured in pairs by two support points of the rotating shaft 6 of each holding member 5 and a support point of the reinforcing member spanned between the support housings. Since the support case is dispersedly supported at three support points closed in a triangular shape, the support case has high support strength, and accordingly, the rigidity of the support case itself can be reduced.

Hereinafter, the present invention will be described in more detail based on embodiments shown in the accompanying drawings.
Embodiment 1
FIG. 2 shows the overall configuration of the image forming apparatus according to the first embodiment.
<Overall configuration of image forming apparatus>
In the figure, an image forming apparatus 20 forms images with toners of a plurality of color components (in this example, yellow (Y), magenta (M), cyan (C), and black (K)), for example, in the horizontal direction. A plurality of image forming units 21 (21a to 21d in this example) arranged at predetermined intervals along the line A, and a sheet S as a recording material is conveyed to each image forming unit 21, and the sheet S is exposed to light. And a conveying device 22 that transfers an image on the body 30.

In the present embodiment, the image forming unit 21 includes a drum-shaped photoconductor 30 that rotates in a predetermined direction, and a charging device (in this example, using a charging roll) 31 that charges the photoconductor 30. A latent image writing device (LED array is used in this example) 32 for writing an electrostatic latent image on the photosensitive member 30 charged by the charging device 31, and the photosensitive member 30 by the latent image writing device 32. A developing device 33 that develops the electrostatic latent image written thereon with the corresponding color toner, and a cleaning device 34 that cleans the residue on the photoreceptor 30 are provided.
Here, as the image forming unit 21, a charging device using corona discharge such as corotron or scorotron may be used as the charging device 31, or a laser scanning device may be used as the latent image writing device 32. Of course, it can be changed.

In the present embodiment, the transport device 22 also serves as the transfer device 40 that transfers an image onto the paper S as described above. In this example, the transfer devices 40 (specifically, 40a to 40d) are respectively installed corresponding to the photoconductors 30 of the image forming units 21 (21a to 21d), and are in contact with the photoconductors 30. A transfer roll 41 that rotates following the photoconductor 30 is provided, and the sheet S is sandwiched and conveyed between the photoconductor 30 and the transfer roll 41. In this example, a transfer voltage from a transfer power supply (not shown) is applied to the transfer roll 41, and a predetermined transfer electric field is formed between the photoconductor 30 and the transfer roll 41. As a result, the image (toner image) on the photoconductor 30 is transferred to the sheet S side.
Furthermore, in the present embodiment, the conveying device 22 holds both ends of the transfer roll 41 of each transfer device 40 (40a to 40d) and holds the transfer roll 41 against the photosensitive member 30 (specifically, a holding mechanism 50). 50a to 50d), a pressure holding mechanism 80 that releasably holds the pressure state of each transfer roll 41 with respect to each photoconductor 30, and a transfer area between each photoconductor 30 and each transfer roll 41. And a guide member 100 for guiding the sheet S along a predetermined conveyance path.

<Transfer roll>
In the present embodiment, the transfer roll 41 has a metal support shaft 42 extending along the axial direction of the photoreceptor 30 as shown in FIGS. 3 to 5A and 5B, and this support shaft. A roll main body 43 having a circular cross section made of a resin or rubber adjusted to a predetermined volume resistivity is formed on the portion excluding both ends of 42, and the roll main body 43 is disposed in contact with the photoreceptor 30. It is a thing.
<Holding mechanism>
The holding mechanism 50 includes a holding arm 51 (specifically 51a and 51b) as a pair of holding members that rotatably holds the both-end support shaft 42 of the transfer roll 41, and a rotation that rotatably supports the holding arm 51. A connecting member that extends in the same direction as the axial direction of the shaft 52 and the transfer roll 41 and connects the pair of holding arms 51 at a portion of the holding arm 51 that is away from the rotating shaft 52 and the support shaft 42 of the transfer roll 41. , And a tension spring 54 as a tension member that pulls the central portion of the length direction of the connecting rod 53 so that the transfer roll 41 is pressed toward the photosensitive member 30.
In particular, in this example, the holding arm 51 includes a rotating shaft 52, a supporting shaft holding portion 55 that rotatably supports the supporting shaft 42 of the transfer roll 41, and a connecting rod 53 that corresponds to an action point portion of the tension spring 54. The connecting portions 56 are formed in a substantially triangular shape arranged near the apexes.
In this example, as shown in FIGS. 5B and 8, the central axis L <b> 1 connecting the rotation shaft 52 of the holding arm 51 and the support shaft 42 of the transfer roll 41 is connected to the rotation shaft 52 of the holding arm 51. The tension spring 54 is arranged at a substantially right angle with respect to a reference line L2 connecting the action point portion.
In this example, the tension spring 54 is pulled in a direction substantially orthogonal to a reference line L2 connecting the rotation shaft 52 of the holding arm 51 and the action point of the tension spring 54. Therefore, in this example, the holding arm 51 presses the transfer roll 41 to the photosensitive member 30 in a direction substantially orthogonal to the direction in which the tensile force Ft is applied by the tension spring 54.
In this example, a common pair of support housings 60 (specifically, 60a and 60b) are disposed on both sides in the axial direction of each transfer roll 41, and each holding mechanism 50 is provided in the support housing 60. A bearing portion 61 that supports the rotating shaft 52 of the holding arm 51 is formed at a predetermined position, and the rotating shaft 52 of each holding arm 51 is supported by the bearing portion 61.

<Pressure holding mechanism>
As shown in FIGS. 2 to 9, the pressure holding mechanism 80 is movable as one movable member that is provided so as to be movable along a direction corresponding to the expansion / contraction direction of each tension spring 54 in association with each holding mechanism 50. A plate 81 is provided.
The movable plate 81 is a long member extending in the direction intersecting the connecting rod 53 below the connecting rod 53 in the vicinity of the central portion in the length direction of the connecting rod 53, and the tension spring 54 of each holding mechanism 50. The hooked piece 82 is provided to be hooked on the one end hooking portion 54a. The other end hooking portion 54 b of the tension spring 54 is hooked on the hooked groove 53 b of the connecting rod 53.
Further, the movable plate 81 is formed with two long hole-like positioning holes 83 and 84 extending in the longitudinal direction. For example, two positioning rods 63 and 64 are hung between the paired support housings 60. The positioning rods 63 and 64 are disposed so as to penetrate the positioning holes 83 and 84 of the movable plate 81, and the movable plate 81 is positioned at a predetermined position.

Further, the pressure holding mechanism 80 has an advance / retreat mechanism 85 that advances and retracts the movable plate 81 along its longitudinal direction. In this example, as shown in FIGS. 4, 6, 7 and 9, the advance / retreat mechanism 85 is provided on the downstream side of the movable plate 81 in the transport direction of the sheet S, and has a predetermined rotation center 86a. And an eccentric cam 86 having an eccentric cam surface 86b and a projecting pin 87 for position regulation that protrudes from a part of the movable plate 81 and abuts against the cam surface 86b of the eccentric cam 86.
Then, by appropriately rotating the eccentric cam 86, for example, as shown in FIGS. 6 and 9A, a span d between the rotation center 86a of the eccentric cam 86 and the cam surface 86b corresponding to the protruding pin 87 is obtained. Under the condition that the predetermined long span d1 is reached, the eccentric cam 86 moves the movable plate 81 in the A direction (tensile direction) in which the tensile force Ft by each tension spring 54 increases, for example, FIG. 7 and FIG. As shown in (b), under the condition that the span d between the rotation center 86a of the eccentric cam 86 and the cam surface 86b corresponding to the protruding pin 87 reaches a predetermined short span d2, the eccentric cam 86 is The movable plate 81 is moved backward in the B direction for releasing the tensile force Ft by each tension spring 54.
Furthermore, the pressure holding mechanism 80 has an operation member 90 for operating the advance / retreat mechanism 85. The operation member 90 is provided, for example, so as to intersect the rotation center 86a of the eccentric cam 86 and the cam center shaft 91 coaxial, and is operated by appropriately rotating the eccentric cam 86. In this example, the movable plate 81 has a through-hole 88 through which the cam central shaft 91 passes. The through-hole 88 is connected to the cam central shaft 91 and the movable plate 81 in the movable range of the movable plate 81 by the advance / retreat mechanism 85. Is formed in a long hole shape so as not to interfere.

<Guide member>
In the present embodiment, the guide member 100 has a plurality of guide ribs 102 at predetermined intervals on a guide plate 101 extending in the axial direction of the transfer roll 41 as shown in FIGS. An inclined surface 103 is formed on the edge of each guide rib 102 on the transfer area side of each image forming portion 21 that is inclined obliquely upward and away from the transfer area.
In particular, in the present embodiment, the transfer roll 41 has a center line connecting the rotation center of the photoconductor 30 and the rotation center of the transfer roll 41 with respect to a reference line O1 extending in the vertical direction through the rotation center of the photoconductor 30. O2 is arranged so as to be displaced upstream in the conveyance direction of the sheet S, and when the sheet S passes through the transfer area between the photosensitive member 30 and the transfer roll 41, the center line O2 is relative to the reference line O1. Since the sheet is inclined by the angle θ, the passing posture of the sheet S passing through the transfer area is adjusted to be slightly inclined downward, and the leading edge of the sheet S is formed at the edge of each guide rib 102 of the guide member 100. The sheet S is brought into contact with the inclined surface 103 and guided toward the sheet guide surface by the guide ribs 102.

<Operation process by pressure holding mechanism>
-Pressure holding operation by the pressure holding mechanism-
In the present embodiment, when the transfer device 40 is disposed at a set position where the transfer device 40 can be transferred to the photoconductor 30, the press roller holding mechanism 80 presses the transfer roll 41 against the photoconductor 30. That's fine.
Specifically, as shown in FIGS. 6 and 9A, the operation member 90 of the advance / retreat mechanism 85 is rotated to the substantially horizontal position, so that the longitudinal direction of the eccentric cam 86 faces the substantially horizontal direction. The eccentric cam 86 may be rotated. Accordingly, the span d between the rotation center 86a of the eccentric cam 86 and the cam surface 86b corresponding to the protruding pin 87 reaches a predetermined long span d1, and the eccentric cam 86 moves the movable plate 81 to the arrow. Move to advance in direction A.
At this time, since each tension spring 54 of each holding mechanism 50 is pulled in the direction of arrow A as the movable plate 81 moves, the tensile force Ft by each tension spring 54 increases and acts on the central portion of the connecting rod 53. To do.
Here, the center span between the rotation shaft 52 of the holding arm 51 and the support shaft holding portion 55 of the transfer roll 41 is r1, and the rotation portion 52 of the holding arm 51 and the connection portion 56 of the connecting rod 53 (the tensile force by the tension spring 54). Assuming that the center-to-center span with respect to the Ft acting point portion is r2, a rotation moment M (specifically, Ft × r2) about the rotation shaft 52 acts on each holding arm 51. The roll 41 is pressed against the photoconductor 30 with a pressing force Fp obtained by dividing the rotational moment M by the span r1.
At this time, the tensile force Ft due to the tension spring 54 acts on the central portion of the connecting rod 53 in the length direction, and the direction of the tension force Ft is uniquely determined along the direction in which the tension spring 54 extends. The direction of action of the tensile force Ft by the tension spring 54 is set to be stable. As described above, since the tensile force Ft by the tension spring 54 stably acts on the central portion in the length direction of the connecting rod 53 in a predetermined direction, the connecting portions of the paired holding arms 51 located at both ends of the connecting rod 53. A tensile force Ft is applied to 56 substantially equally, and the transfer roll 41 is pressed almost uniformly along the axial direction with respect to the photoreceptor 30.
Further, since the holding arm 51 is formed in a triangular shape, the holding arm 51 has a high bending rigidity, and accordingly, a tensile force Ft by the tension spring 54 is applied to the connecting portion 56 of the holding arm 51 with the connecting rod 53. Even if it acts, there is little concern that the holding arm 51 is deformed by the tensile force Ft.
The pressure Fp applied by the transfer roll 41 to the photoconductor 30 is selected in advance in consideration of the transfer performance in the transfer area between the photoconductor 30 and the transfer roll 41, and the tensile force Ft generated by the tension spring 54 is described above. A value necessary for obtaining the applied pressure Fp is selected.

−Pressure release operation by pressure holding mechanism−
In the present embodiment, when the transfer device 40 is temporarily retracted from the set position with respect to the photoconductor 30, the pressure holding mechanism 80 releases the pressure state of the transfer roll 41 with respect to the photoconductor 30. What should I do?
Specifically, as shown in FIGS. 7 and 9B, the longitudinal direction of the eccentric cam 86 is changed to a substantially vertical direction by rotating the operation member 90 of the advance / retreat mechanism 85 from a substantially horizontal position to a substantially vertical position. The eccentric cam 86 may be rotated so as to face. As a result, the span d between the rotation center 86a of the eccentric cam 86 and the cam surface 86b corresponding to the protruding pin 87 becomes a predetermined short span d2, and the movable plate 81 has the span d due to the elastic force of the tension spring 54. The difference Δd (corresponding to d1−d2) is moved back in the arrow B direction. As a result, the tensile force Ft (see FIG. 9A) due to the tension spring 54 is reduced or released, and accordingly, the pressure Fp of the transfer roll 41 against the photosensitive member 30 (FIG. 9A). The holding arm 51 rotates about the rotation shaft 52 to the position where the tension spring 54 exists, and the transfer roll 41 is temporarily retracted to a position away from the photoconductor 30.
In this state, since the transfer roll 41 is temporarily retracted from the photoconductor 30, for example, when the paper S is jammed in the transfer area between the photoconductor 30 and the transfer roll 41, or at the periphery of the transfer area. When performing maintenance, by performing the pressure release operation by the pressure holding mechanism 80, it is possible to easily perform the operation of removing the sheet S and the maintenance of the peripheral portion of the transfer area.

-Support structure for holding mechanism and pressure holding mechanism-
In the present embodiment, the transfer devices 40 are respectively arranged corresponding to the plurality of photoconductors 30, and the transfer rolls 41 of the respective transfer devices 40 are held by the holding mechanisms 50.
In this example, as shown in FIG. 7, the rotation shaft 52 of the holding arm 51 in each holding mechanism 50 is supported by a bearing portion 61 of a common support housing 60 (60a, 60b) in a pair configuration.
Further, for example, two positioning rods 63 and 64 are spanned between the paired support housings 60, and the movable plate 81 of the pressurizing and holding mechanism 80 is inserted into the two positioning holes 83 and 84. It is positioned by passing through 64.
In particular, in this example, the positioning rod 63 is the rotating shaft 52 of the holding arm 51 in the first and second holding mechanisms 50 (50a, 50b) of the paired support housings 60 (60a, 60b). Between the two bearing portions 61 and a portion separated from the straight line connecting the two bearing portions 61. The positioning rod 64 is located between the bearing portions 61 of the rotating shaft 52 of the holding arm 51 in the third and fourth holding mechanisms 50 (50c, 50d) and away from the straight line connecting the both bearing portions 61. It is stretched over.
For this reason, the first to fourth holding mechanisms 50 (50a to 50d) and the pressure holding mechanism 80 are the same as the rotation shaft 52 of the holding arm 51 of each of the adjacent holding mechanisms 50 (50a, 50b or 50c, 50d). Two support points P1 and P2 and a support point P3 of the positioning rod 63 or 64 that is spanned between the paired support housings 60 and also serves as a reinforcing member are closed in a triangular shape with respect to the paired support housings 60. In addition, since the support is distributed and supported at the three support points (P1 to P3), the support strength of the paired support housing 60 is high, and accordingly, the rigidity of the support housing 60 itself can be reduced.

In the present embodiment, the holding arm 51 of each holding mechanism 50 is formed in a substantially triangular shape, but is not limited to this. For example, the deformation shown in FIGS. 10 (a) and 10 (b) It is possible to adopt this form.
10 (a) uses a substantially L-shaped holding arm 151 as the holding mechanism 50 for the transfer roll 41, and the support shaft of the transfer roll 41 is attached to the tip of one arm portion 151a of the holding arm 151. A holding portion 155 is provided, a connecting portion 156 of a connecting rod 153 as a connecting member is provided at the tip of the other arm portion 151b, and a rotating shaft 152 is provided at a branch portion of both arm portions 151a and 151b.
Here, the tensile force by the tension spring 54 is Ft, the pressing force of the transfer roll 41 against the photoreceptor 30 is Fp, and the span between the centers of the rotation shaft 152 and the support shaft holding portion 155 of the transfer roll 41 of one arm portion 151a. Is r1, and the center span between the rotation shaft 152 and the connecting portion 156 of the other arm portion 151b is r2, and Ft and Fp are substantially orthogonal to each other, Fp × r1 = Ft × r2. The transfer roll 41 is pressed against the photoconductor 30 under conditions that satisfy the relationship.
Further, in the modification shown in FIG. 10B, a substantially L-shaped holding arm 151 is used as the holding mechanism 50 of the transfer roll 41, similarly to the modification shown in FIG. However, unlike the modification shown in FIG. 10A, the rotation shaft 152 is provided at the tip of one arm 151a of the holding arm 151, and the connecting portion 156 of the connecting rod 153 is provided at the tip of the other arm 151b. And a support shaft holding portion 155 of the transfer roll 41 is provided at a branch portion between both arm portions 151a and 151b.
Here, the tensile force by the tension spring 54 is Ft, the pressing force of the transfer roll 41 against the photoreceptor 30 is Fp, and the span between the centers of the rotation shaft 152 and the support shaft holding portion 155 of the transfer roll 41 of one arm portion 151a. R1, the span between the centers of the rotating shaft 152 and the connecting portion 156 of the connecting rod 153 is h, the angle between the center line corresponding to r1 and the center line corresponding to h is α, and Ft and Fp are substantially orthogonal to each other. If the relationship is satisfied, the transfer roll 41 is pressed against the photoconductor 30 under the condition satisfying the relationship of Fp × r1 = Ft · cos α × h.

Comparison Mode Next, in evaluating the performance of the holding mechanism 50 used in the transfer device 22 according to the present embodiment, the holding mechanism used in the transfer device according to the comparison mode 1 shown in FIG. And the holding mechanism used for the conveyance apparatus which concerns on the comparison form 2 shown to FIG.11 (b) (c) is demonstrated.
First, the holding mechanism 160 in the first comparative example shown in FIG. 11A urges the both end support shafts 42 of the transfer roll 41 with a pair of urging springs 161 and 162, and the transfer roll 41 with respect to the photoreceptor 30. Is to be pressurized.
In this embodiment, since the biasing force of the pair of biasing springs 161 and 162 varies by about ± 10%, for example, there is a concern that the pressing force of the transfer roll 41 against the photosensitive member 30 is likely to vary at both ends in the axial direction.
11B and 11C, the holding mechanism 170 according to the second comparative example has a pair of substantially L-shaped holding arms 171 disposed at both ends of the transfer roll 41, and one of the holding arms 171 is arranged. The rotating shaft 172 is provided at the tip of the arm 171a, the connecting rod 173 is stretched over the tip of the other arm 171b, and both end support shafts 42 of the transfer roll 41 are connected to the branching portions of both the arms 171a and 171b. Further, the transfer roller 41 is pressed against the photosensitive member 30 by applying a pressing force by the pressing spring 174 to the central portion of the connecting rod 173 in the length direction.
In this embodiment, substantially the same as the deformation mode shown in FIG. 10B, the pressing force by the pressing spring 174 is Fn, the pressing force of the transfer roll 41 against the photosensitive member 30 is Fp, and the rotating shaft of one arm portion 171a. The center span between the center 172 and the support shaft 42 of the transfer roll 41 is r1, the center span between the rotation shaft 172 and the connecting rod 173 is h, and the angle between the center line corresponding to r1 and the center line corresponding to h is Assuming that β, Fn, and Fp are substantially orthogonal to each other, the transfer roll 41 is pressed against the photoconductor 30 under a condition that satisfies the relationship of Fp × r1 = Fn · cos β × h.
However, in this aspect, the bearing surface of the pressing spring 174 is arranged obliquely due to variations in the outer diameter and rotation fulcrum of the transfer roll 41, and the pressing spring 174 acts on the connecting rod 173 such as buckling during the pressing operation. There is a concern that the pressing force Fn varies and the pressing force Fp of the transfer roll 41 against the photoconductor 30 tends to become unstable.
On the other hand, the holding mechanism 50 according to this embodiment is preferable in that the transfer roll 41 can be stably pressed against the photoconductor 30 unlike the first and second embodiments.

Embodiment 2
FIG. 12 shows a main part of a conveying device used in the image forming apparatus according to the second embodiment.
In the figure, unlike the first embodiment, the conveying device 22 is mainly intended to convey a sheet S as a recording material, and includes a plurality (four in this example) of driving conveying rolls 200 (specifically, 201 to 204), and a driven transport roll 210 (specifically 211 to 214) that contacts the drive transport roll 200 as an opposing roll and rotates following the drive transport roll 200.
In the present embodiment, the drive transport rolls 200 (201 to 204) transmit a driving force from a drive motor 205 as a drive source via a drive transmission mechanism 206 such as a gear train.
The driven transport rolls 210 (211 to 214) are respectively held by the holding mechanisms 250, and each holding mechanism 250 (specifically, 251 to 254) is driven and transported to the drive transport roll 200 by the pressure holding mechanism 280. The pressure state of the roll 210 is held releasably.
Here, each holding mechanism 250 includes a holding arm 261 as a pair of holding members that rotatably holds the both-end support shafts 215 of the driven transport roll 210, and a rotating shaft 262 that rotatably supports the holding arms 261. Connection as a connecting member that extends in the same direction as the axial direction of the driven transport roll 210 and connects the pair of holding arms 261 at a portion of the holding arm 261 that is away from the rotating shaft 262 and the support shaft 215 of the driven transport roll 210. A rod 263 and a tension spring 264 as a tension member that pulls the central portion in the length direction of the connecting rod 263 so that the driven transport roll 210 is pressurized toward the drive transport roll 200 are provided.
The pressure holding mechanism 280 has a movable plate 281 as one movable member provided so as to be movable along a direction corresponding to the expansion / contraction direction of the tension spring 264 in association with each holding mechanism 250 (251 to 254). The movable plate 281 includes a hooked piece 282 that is hooked to one hook portion of the tension spring 264 of each holding mechanism 250. The other end hooking portion of the tension spring 264 is hooked in a hooked groove (not shown) of the connecting rod 263.
Further, the pressure holding mechanism 280 includes an advance / retreat mechanism 285 that advances and retracts the movable plate 281 along its longitudinal direction, and an operation member (not shown) that operates the advance / retreat mechanism 285.
In this example, the advance / retreat mechanism 285 is provided on the downstream side in the transport direction of the sheet S of the movable plate 281 and has a cam surface 286b that is eccentric with respect to a predetermined rotation center 286a, as in the first embodiment. And an eccentric cam 286 that protrudes from a portion of the movable plate 281 and abuts against a cam surface 286b of the eccentric cam 286. The eccentric cam 286 of the advancing / retracting mechanism 285 is moved by an operating member. The movable plate 281 is advanced and retracted by appropriately rotating.
In FIG. 12, reference numeral 290 denotes a transport housing that houses the driven transport roll 210, the holding mechanism 250, and the pressure holding mechanism 280, and reference numerals 291 and 292 pass through the positioning holes 283 and 284 provided in the movable plate 281. The positioning rod is hung on the transport housing 290.

Therefore, according to the present embodiment, during the pressurizing operation by the pressurizing and holding mechanism 280, the movable plate 281 is moved in the advance direction along the transport direction of the paper S by the advance / retreat mechanism 285, thereby What is necessary is just to hold | maintain the pressurization state of the driven conveyance roll 210 with respect to the drive conveyance roll 200 by applying the tensile force by the tension spring 264. FIG.
Also in this aspect, the driven transport roll 210 is pressed almost uniformly against the drive transport roll 200 by the same action as in the first embodiment.
On the other hand, during the pressure release operation by the pressure holding mechanism 280, the movable plate 281 is moved in the retreat direction different from the transport direction of the paper S by the advance / retreat mechanism 285, whereby the tensile force by the tension spring 264 of each holding mechanism 250. May be reduced or released, thereby releasing the pressure state of the driven conveyance roll 210 with respect to the driving conveyance roll 200.
In this embodiment, the transport device 22 transports the paper S in a substantially horizontal direction, and the drive transport roll 200 is disposed on the upper side of the driven transport roll 210. However, the present invention is not limited to this. For example, the present invention is also applied to an aspect in which the drive conveyance roll 200 is disposed below the driven conveyance roll 210 or an aspect in which the conveyance path of the paper S extends in a direction other than the substantially horizontal direction, for example, in the substantially vertical direction. Of course, it can be applied.

  DESCRIPTION OF SYMBOLS 1 (1a-1d) ... Image holding body, opposing member, 2 ... Conveying device, 3 (3a-3d) ... Conveying member, 3s ... Support shaft, 4 ... Holding mechanism, 5 ... Holding member, 6 ... Rotating shaft, 7 ... connecting member, 8 ... tension member, 10 ... pressure holding mechanism, Fp ... pressure, Ft ... tensile force, S ... recording material

Claims (14)

A rotatable conveying member that opposes the rotatable opposing member and conveys the recording material while being sandwiched between the opposing member;
A holding mechanism that holds both ends of the conveying member and pressurizes the conveying member against the opposing member;
The holding mechanism includes a pair of holding members that rotatably hold both end support shafts of the transport member;
A rotating shaft that rotatably supports the holding member;
A connecting member that extends in the same direction as the axial direction of the conveying member, and that connects the holding members at a position away from the rotating shaft and the support shaft of the conveying member among the holding members;
A tension member that pulls a central portion in the length direction of the connecting member so that the conveying member is pressurized toward the opposing member;
A conveying apparatus comprising: In the conveying apparatus of Claim 1,
The transporting device, wherein the tension member is pulled in a direction substantially orthogonal to a reference line connecting a rotation axis of the holding member and an action point of the tension member. In the conveyance apparatus of Claim 1 or 2,
The holding member is formed in a substantially triangular shape in which the rotating shaft, the supporting shaft holding portion of the conveying member, and the action point portion of the tension member are arranged in the vicinity of the apexes, respectively. apparatus. In the conveyance apparatus in any one of Claim 1 thru | or 3,
A central axis connecting the rotation shaft of the holding member and the support shaft of the transport member is disposed substantially perpendicular to a reference line connecting the rotation shaft of the holding member and the action point of the tension member. A conveying device characterized by the above. In the conveyance apparatus in any one of Claim 1 thru | or 3,
The transport device according to claim 1, wherein the holding member presses the transport member against the opposing member in a direction substantially orthogonal to a direction in which a tensile force is applied by the tension member. In the conveyance apparatus in any one of Claim 1 thru | or 5,
A conveying apparatus comprising: a pressure holding mechanism that applies a tensile force by the tension member to the holding member so as to hold a pressure state of the conveying member with respect to the opposing member. The transport apparatus according to claim 6, wherein
The pressure holding mechanism includes a pressure release unit that reduces a state in which a tensile force is applied to the holding member by the tension member so as to release a pressure state of the transport member with respect to the facing member. A transport device. In the conveyance apparatus of Claim 7,
The pressure holding mechanism includes a movable member that can be moved to apply or reduce a tensile force by the tension member, an advance / retreat mechanism that moves the movable member forward / backward, and an operation member that operates the advance / retreat mechanism. A conveying device characterized by the above. An image holding member as an opposing member that forms and holds an image, and a conveying device that conveys a recording material so as to pass through an image transfer area of the image holding member,
An image forming apparatus using the transport device according to claim 1 as the transport device. The image forming apparatus according to claim 9.
The conveying member of the conveying device faces an image holding member as a rotatable counter member, conveys the recording material between the image holding member and conveys an image formed on the image holding member. An image forming apparatus, wherein the image forming apparatus is a transfer member to be transferred onto the image forming apparatus. The aspect having a plurality of image carriers in the image forming apparatus according to claim 10,
The holding mechanism of the transport device is provided corresponding to each image holding body,
Each holding mechanism is commonly used to apply or reduce the tensile force of each of the tension members to the holding member so as to hold or release the pressure state of the transfer member as each of the conveying members with respect to each of the image holding bodies. An image forming apparatus comprising a pressure holding mechanism. The image forming apparatus according to claim 11, wherein a pair of common support housings are provided on both sides in the axial direction of the conveying member held by each holding mechanism.
Each of the holding mechanisms is an image forming apparatus in which a rotation shaft of each holding member is supported by the common support housing. The image forming apparatus according to claim 11.
The pressurizing and holding mechanism includes a hooked portion that is hooked by the tension member of each holding mechanism, and a movable member that is movably provided to apply or reduce a tensile force by each tension member, and the movable member. An image forming apparatus comprising: an advance / retreat mechanism for moving a member forward and backward; and an operation member for operating the advance / retreat mechanism. The image forming apparatus according to claim 12.
The common support housing of the pair configuration is positioned between two adjacent support positions among the support positions of the rotation shafts of the holding members and at a position away from a straight line connecting the two support positions. An image forming apparatus comprising one or a plurality of reinforcing members that are stretched while being connected to each other.

Images