JP5346891B2 - PRESSING DEVICE AND IMAGE FORMING DEVICE HAVING THE SAME - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pressing device which converts rotation output of an output part for displacement into linear motion to press and release a part to be pressed by the part to be pressed and in which the output part for displacement does not become overloaded, and to provide an image forming apparatus equipped with the pressing device. <P>SOLUTION: The pressing device 100 of the image forming apparatus 1 comprises an approach member displacement mechanism 120 for displacing a second member K from an approach state to a separation state. The approach member displacement mechanism 120 comprises: a first rotation transmission body 134 for receiving transmission of torque of an output part 160 for displacement; a second rotation transmission body 138 for receiving transmission of torque of the first rotation transmission body 134; and a rotation linear motion conversion part 140 for converting rotational motion of the second rotation transmission body 138 to linear motion and making the second member K in the separation state. The second rotation transmission body 138 receives transmission of torque of the first rotation transmission body 134 with rotation of a first oval gear 134 so that speed reduction ratio from the first rotation transmission body 134 to the second rotation transmission body 138 becomes smaller. <P>COPYRIGHT: (C)2012,JPO&amp;INPIT

Description

  The present invention relates to a pressing device that presses a second member disposed so as to be displaceable in an approaching state or a spaced apart state approaching the first member so as to be in the separated state, and an image forming apparatus including the pressing device.

  In general, an image forming apparatus such as a copying machine, a printer, or a facsimile machine includes an image carrier (photosensitive drum), a developer that converts an electrostatic latent image formed on the image carrier into a toner image, and toner. A toner storage unit (also referred to as a “toner cartridge”) for storage, a transfer unit for transferring a toner image formed on the image carrier onto a sheet of paper via an intermediate transfer belt, and a toner image transferred to the paper A fixing unit that fixes the paper to a sheet, and a sheet conveying unit that conveys the sheet to a transfer unit, a fixing unit, or the like.

The intermediate transfer belt is stretched around a drive roller, a tension roller, or the like so that the intermediate transfer belt can approach or separate from the photosensitive drum. For example, the image forming apparatus includes a primary transfer roller disposed on the side opposite to the photosensitive drum in the intermediate transfer belt, and a pressing device having a spring that presses the primary transfer roller with the intermediate transfer belt facing the photosensitive drum. A pressure release device for releasing the pressure of the primary transfer roller (see, for example, Patent Document 1).
The press release device of the image forming apparatus described in Patent Literature 1 includes a conversion mechanism that converts the rotational motion of the output shaft of the motor serving as the displacement output unit into linear motion. The conversion mechanism includes a worm wheel and a spur gear, and a worm wheel and a helical gear. When the motor operates, the press release device moves the primary transfer roller to the side opposite to the photosensitive drum on the intermediate transfer belt by the conversion mechanism.

JP 2009-265337 A

However, in the image forming apparatus described in Patent Document 1, since the conversion mechanism is configured by a worm wheel, a spur gear, or the like, the gear ratio of the conversion mechanism does not change while the primary transfer roller is moved. That is, if the output of the motor is constant, the output converted by the conversion mechanism is also constant.
On the other hand, as the intermediate transfer belt and the photosensitive drum are separated greatly, the spring deflection of the pressing device increases. For this reason, the motor is overloaded as the spring deflection of the pressing device increases. For example, when the motor is overloaded, the load torque of the motor increases, and there is a concern that the motor consumes a large amount of current or the gears of the conversion mechanism are damaged.
In the image forming apparatus, there are many types of press releasing devices other than the primary transfer roller. Since these press release devices are also operated by the rotation output of the output shaft of the motor, there is a concern about the motor overload similar to the press release device for the primary transfer roller.

  According to the present invention, the pressing device that presses the second member, which is displaceably placed in the approaching state or the spaced apart state approaching the first member, to be in the separated state, separates the second member from the position in the approaching state. An object of the present invention is to provide a pressing device in which the displacement output section is less likely to be overloaded in an operation of displacing to the position, and an image forming apparatus including the pressing device.

  The present invention is a pressing device that presses a second member, which is displaceably placed in an approaching state or a spaced apart state approaching the first member, so as to be in the separated state, wherein the second member is moved to the approaching state. A pressing force application mechanism that presses the state to a state, an approach member displacement mechanism that displaces the second member from the approach state to the separated state, and a displacement output unit that operates the approach member displacement mechanism, The approach member displacement mechanism includes a first rotation transmission body that receives transmission of the rotational force of the output unit for displacement, a second rotation transmission body that receives transmission of the rotation force of the first rotation transmission body, and the second rotation. A rotation / linear motion conversion unit that converts the rotational motion of the transmission body into a reciprocating motion and places the second member in the separated state, and the second rotation transmission body rotates the first rotation transmission body. Accordingly, from the first rotation transmission body to the first rotation Transmission of rotational force of the first rotation transmission body so that a reduction ratio to the rotation transmission body is reduced and the first member and the second member are displaced from the separated state to the approaching state. The present invention relates to a pressing device for an image forming apparatus.

  The first rotation transmission body has a first non-circular tooth portion whose pitch circle is non-circular, the second rotation transmission body meshes with the first non-circular tooth portion, and the pitch circle is non-circular. It is preferable to have a circular second non-circular tooth.

  The pressing force applying mechanism presses the second member against the first member as the first member and the second member are displaced from the approaching position to the separated position. It is preferable to have a spring that increases the pressing force.

  The present invention relates to an image forming apparatus including an image forming unit that forms an image on a sheet and the pressing device described above.

  According to the present invention, the second rotation transmission body rotates the first rotation so that the reduction ratio from the first rotation transmission body to the second rotation transmission body decreases as the first rotation transmission body rotates. Receives the transmission force of the transmission body. For this reason, the pressing device that presses the second member disposed so as to be displaceable in the approaching state or the spaced-apart separation state approaching the first member into the separation state causes the second member to be in the separation state from the approaching position. In the operation of displacing to a position, it is possible to provide a pressing device in which the displacement output section is less likely to be overloaded, and an image forming apparatus including the pressing device.

FIG. 2 is a front view for explaining the arrangement of each component in the copier 1 as the first embodiment of the present invention. FIG. 2 is a perspective view for explaining an intermediate transfer belt holding frame K as a second member provided in the image forming unit GK shown in FIG. 1. FIG. 6 is another perspective view for explaining an intermediate transfer belt holding frame K as a second member provided in the image forming unit GK shown in FIG. 2. It is an expansion perspective view of the press apparatus 100 shown in FIG. FIG. 2 is a schematic diagram for explaining a state in which the photosensitive drums 2a, 2b, and 2c and the intermediate transfer belt 7 are in an approaching state during color printing in the copier 1 shown in FIG. FIG. 2 is a schematic diagram for explaining a state in which the photosensitive drums 2a, 2b, and 2c and the intermediate transfer belt 7 are in a separated state during black and white printing in the copier 1 shown in FIG. FIG. 5 is a view for explaining the shape and positional relationship between a first elliptical gear 134 that is a first rotation transmission body, a second elliptical gear 138 that is a second rotation transmission body, and a cam plate 141 of the pressing device 100 of FIG. 4. . It is a graph which shows the mode of a change of the rotational speed ratio of the 1st elliptical gear 134 of the 1st rotation transmission body shown in FIG. 7, and the 2nd elliptical gear 138 of a 2nd rotation transmission body. It is an expansion perspective view for demonstrating operation | movement of the press apparatus 100 shown in FIG. It is an expansion perspective view for demonstrating operation | movement of the press apparatus 100 following FIG. It is a perspective view for demonstrating the positional relationship of the heating roller 9a and the pressurization roller 9b in the approaching state of the fixing part 9 of the copying machine 1a as 2nd Embodiment of this invention. FIG. 12 is a perspective view for explaining a positional relationship between a heating roller 9a and a pressure roller 9b in a separated state of the fixing unit 9 of the copier 1a shown in FIG.

Hereinafter, a copying machine 1 according to a first embodiment of the image forming apparatus of the present invention will be described with reference to the drawings.
As shown in FIGS. 1 to 6, the overall structure of a copier 1 as an image forming apparatus in the present embodiment will be described. FIG. 1 is a front view for explaining the arrangement of each component in the copier 1 as the first embodiment of the present invention. FIG. 2 is a perspective view for explaining an intermediate transfer belt holding frame K as a second member provided in the image forming unit GK shown in FIG. FIG. 3 is another perspective view for explaining the intermediate transfer belt holding frame K as the second member provided in the image forming unit GK shown in FIG.
4 is an enlarged perspective view of the pressing device 100 shown in FIG. FIG. 5 is a schematic diagram for explaining a state where the photosensitive drums 2a, 2b, and 2c and the intermediate transfer belt 7 are in an approaching state during color printing in the copier 1 shown in FIG. FIG. 6 is a schematic diagram for explaining a state in which the photosensitive drums 2a, 2b, and 2c and the intermediate transfer belt 7 are in a separated state during black and white printing in the copier 1 shown in FIG.

<Copy machine 1>
As shown in FIG. 1, a copying machine 1 as an image forming apparatus includes an image reading device 200 arranged on the upper side of the copying machine 1 and image information from the image reading device 200 arranged on the lower side of the copying machine 1. And an apparatus main body M that forms a toner image on a sheet T as a sheet-like transfer material.

<Image Reading Device 200>
The image reading apparatus 200 will be described.
As shown in FIG. 1, the image reading apparatus 200 includes a lid member 70 and a reading unit 201 that reads an image of a document G.
The lid member 70 is connected to the reading unit 201 so as to be opened and closed by a connecting unit (not shown). The lid member 70 has a function of protecting a reading surface 202A described later.

  The reading unit 201 reads by the reading surface 202A, a lamp 240 as a light source disposed in the internal space 204, a plurality of mirrors 221, 222, and 223, an imaging lens 230, a CCD 235 as a reading unit, and a CCD 235. A CCD substrate 236 that performs predetermined processing on the received image data and outputs the image data to the apparatus main body M side.

The reading surface 202A is formed along the upper surface in the vertical direction of the contact glass 202 on which the document G is placed.
The reading unit 201 includes a first frame 211 and a second frame 212 that are arranged in the internal space 204 and move in a direction parallel to the reading surface 202A. The lamp 240 and the mirror 221 described above are accommodated in the first frame 211. The mirrors 222 and 223 are accommodated in the second frame 212.

  In the internal space 204 of the reading unit 201, the plurality of mirrors 221, 222, and 223 form an optical path H for allowing light from the original G to enter the imaging lens 230. In addition, since the first frame 211 moves at a constant speed A in the sub-scanning direction X and the second frame 212 moves at a constant speed A / 2 in the sub-scanning direction X, the optical path H can be used even during an image reading operation. The length of is kept constant. Thereby, the image of the document G placed on the reading surface 202A is read.

The apparatus main body M will be described.
The apparatus main body M includes an image forming unit that forms a predetermined image on the paper T based on predetermined image information, and a paper supply / discharge that feeds the paper T to the image forming unit and discharges the paper T on which the image is formed. And a paper portion.

  The image forming unit GK includes photosensitive drums 2a, 2b, 2c, and 2d as image carriers (photosensitive members), charging units 10a, 10b, 10c, and 10d, and laser scanner units 4a, 4b, and 4c as exposure units. 4d, developing devices 16a, 16b, 16c, 16d, toner cartridges 5a, 5b, 5c, 5d, toner supply units 6a, 6b, 6c, 6d, drum cleaning units 11a, 11b, 11c, 11d, The static eliminators 12a, 12b, 12c, and 12d, the intermediate transfer belt 7, the primary transfer rollers 37a, 37b, 37c, and 37d, the secondary transfer roller 8, the opposing roller 18, and the fixing unit 9 are provided.

  The paper feed / discharge unit KH includes a paper feed cassette 52, a manual paper feed unit 64, a conveyance path L for paper T, a registration roller pair 80, a first paper discharge unit 50a, and a second paper discharge unit 50b. Prepare.

Hereinafter, each configuration of the image forming unit GK and the paper supply / discharge unit KH will be described in detail.
<Image forming unit GK>
First, the image forming unit GK will be described.
In the image forming unit GK, charging by the charging units 10a, 10b, 10c, and 10d and laser scanner units 4a, 4b are sequentially performed from the upstream side to the downstream side with respect to the respective surfaces of the photosensitive drums 2a, 2b, 2c, and 2d. 4c, 4d exposure, development units 16a, 16b, 16c, 16d development, intermediate transfer belt 7 and primary transfer rollers 37a, 37b, 37c, 37d primary transfer, static eliminators 12a, 12b, 12c, 12d Static elimination and cleaning by the drum cleaning units 11a, 11b, 11c, and 11d are performed.

  In the image forming unit GK, the secondary transfer by the intermediate transfer belt 7, the secondary transfer roller 8 and the counter roller 18, and the fixing by the fixing unit 9 are performed.

  The photosensitive drums 2a, 2b, 2c, and 2d are made of cylindrical members and function as a photosensitive member or an image carrier. Each of the photosensitive drums 2a, 2b, 2c, and 2d has a rotation shaft that extends in a direction (in the direction of arrow Y) perpendicular to the traveling direction of the intermediate transfer belt 7 (in the direction of arrow X). Each of the photosensitive drums 2a, 2b, 2c, and 2d is disposed in the apparatus main body M so as to be rotatable around the respective rotation axes of the photosensitive drums 2a, 2b, 2c, and 2d. An electrostatic latent image is formed on the surface of each of the photosensitive drums 2a, 2b, 2c, and 2d.

  The charging units 10a, 10b, 10c, and 10d are arranged to face the surfaces of the photosensitive drums 2a, 2b, 2c, and 2d, respectively. The charging units 10a, 10b, 10c, and 10d uniformly charge the surface of each of the photosensitive drums 2a, 2b, 2c, and 2d negatively (minus polarity) or positively (plus polarity).

  The laser scanner units 4a, 4b, 4c, and 4d function as exposure units, and are spaced apart from the surfaces of the photosensitive drums 2a, 2b, 2c, and 2d. Each of the laser scanner units 4a, 4b, 4c, and 4d includes a laser light source (not shown), a polygon mirror, a polygon mirror driving motor, and the like.

  Each of the laser scanner units 4a, 4b, 4c, and 4d scans and exposes the surfaces of the photosensitive drums 2a, 2b, 2c, and 2d based on the image information related to the image read by the reading unit 201. Scanning exposure is performed by each of the laser scanner units 4a, 4b, 4c, and 4d, so that charges charged on the surfaces of the photosensitive drums 2a, 2b, 2c, and 2d are removed. Thereby, electrostatic latent images are formed on the respective surfaces of the photosensitive drums 2a, 2b, 2c, and 2d.

  The developing devices 16a, 16b, 16c, and 16d are provided corresponding to the photosensitive drums 2a, 2b, 2c, and 2d, respectively, and are disposed to face the surfaces of the photosensitive drums 2a, 2b, 2c, and 2d. Each of the developing devices 16a, 16b, 16c, and 16d develops a toner image of each color by attaching the toner of each color to the electrostatic latent image formed on the photosensitive drums 2a, 2b, 2c, and 2d (photosensitive drum). A toner image is formed on the surface). Each of the developing devices 16a, 16b, 16c, and 16d corresponds to four toner colors of yellow, cyan, magenta, and black. Each of the developing devices 16a, 16b, 16c, and 16d includes a developing roller that can be disposed opposite to the surface of the photosensitive drums 2a, 2b, 2c, and 2d, a stirring roller for stirring the toner, and the like.

  The toner cartridges 5a, 5b, 5c, and 5d are provided corresponding to the developing devices 16a, 16b, 16c, and 16d, respectively. The toner cartridges 5a, 5b, 5c, and 5d store toners of respective colors supplied to the developing devices 16a, 16b, 16c, and 16d, respectively. The toner cartridges 5a, 5b, 5c, and 5d contain yellow toner, cyan toner, magenta toner, and black toner, respectively.

  The toner supply units 6a, 6b, 6c, and 6d are provided corresponding to the toner cartridges 5a, 5b, 5c, and 5d and the developing devices 16a, 16b, 16c, and 16d, respectively. The toners of the respective colors accommodated in 5d are supplied to the developing devices 16a, 16b, 16c, and 16d, respectively.

The toner images of the respective colors developed on the photosensitive drums 2a, 2b, 2c, and 2d are sequentially transferred to the intermediate transfer belt 7. The intermediate transfer belt 7 is stretched around a driving roller 35, a counter roller 18, a tension roller 36, and the like. Since the tension roller 36 biases the intermediate transfer belt 7 from the inside to the outside, a predetermined tension is applied to the intermediate transfer belt 7.
As shown in FIGS. 2 to 4, the intermediate transfer belt 7, the primary transfer rollers 37a, 37b, 37c, and 37d, the driving roller 35, and the tension roller 36 have a frame shape that extends in the direction of the arrow X and the direction of the arrow Y. It is held by an intermediate transfer belt holding frame K (see FIGS. 2 and 3). The drive roller 35 side of the intermediate transfer belt holding frame K in the direction of the arrow X is supported by the apparatus main body M so as to be swingable in the direction of the arrow Z around the rotation axis of the drive roller 35. The counter roller 18 side of the intermediate transfer belt holding frame K in the direction of arrow X is supported by a pressing device 100 (see FIGS. 2 and 3) attached to the apparatus body M so as to be swingable in the direction of arrow Z. Yes.

  Primary transfer rollers 37a, 37b, 37c, and 37d are arranged to face each other on the side opposite to the photosensitive drums 2a, 2b, 2c, and 2d with the intermediate transfer belt 7 interposed therebetween.

A predetermined portion of the intermediate transfer belt 7 is sandwiched between the primary transfer rollers 37a, 37b, 37c, and 37d and the photosensitive drums 2a, 2b, 2c, and 2d, respectively.
The primary transfer rollers 37a, 37b, and 37c are supported by the intermediate transfer belt holding frame K. On the other hand, the primary transfer roller 37d is supported by the apparatus main body M.

  As shown in FIG. 5, the primary transfer rollers 37 a, 37 b, and 37 c are moved through the intermediate transfer belt holding frame K by the approach member displacement mechanism 120 (see FIGS. 3 and 4) of the pressing device 100. When being brought close to 2b and 2c, the sandwiched predetermined portion is pressed against the surface of each of the photosensitive drums 2a, 2b, 2c and 2d. Primary transfer nips N1a, N1b, N1c, and N1d are formed between the photosensitive drums 2a, 2b, 2c, and 2d and the primary transfer rollers 37a, 37b, 37c, and 37d, respectively. In the primary transfer nips N1a, N1b, N1c, and N1d, the respective color toner images developed on the photosensitive drums 2a, 2b, 2c, and 2d are sequentially transferred to the intermediate transfer belt 7. As a result, a color toner image is formed on the intermediate transfer belt 7.

  Also, as shown in FIG. 6, the primary transfer rollers 37a, 37b, and 37c are separated from the photosensitive drums 2a, 2b, and 2c via the intermediate transfer belt holding frame K by the approach member displacement mechanism 120 of the pressing device 100. When in the separated state, the sandwiched predetermined portion is pressed only against the surface of the photosensitive drum 2d. Therefore, only the primary transfer nip N1d is formed between the photosensitive drum 2d and the primary transfer roller 37d. In the primary transfer nip N1d, the black toner image developed on the photosensitive drum 2d is transferred to the intermediate transfer belt 7. As a result, a black toner image is formed on the intermediate transfer belt 7.

  As shown in FIG. 1, toner images developed on the photosensitive drums 2a, 2b, 2c, and 2d, respectively, are intermediately applied to the primary transfer rollers 37a, 37b, 37c, and 37d by a voltage application unit (not shown). A primary transfer bias for transferring to the transfer belt 7 is applied.

  The static eliminators 12a, 12b, 12c, and 12d are arranged to face the surfaces of the photosensitive drums 2a, 2b, 2c, and 2d, respectively. The static eliminators 12a, 12b, 12c, and 12d respectively irradiate the surfaces of the photosensitive drums 2a, 2b, 2c, and 2d to irradiate light, and the photosensitive drums 2a, 2b, and 2c after the primary transfer is performed. 2d, each surface is neutralized (charge is removed).

  Each of the drum cleaning units 11a, 11b, 11c, and 11d is disposed to face the surface of the photosensitive drums 2a, 2b, 2c, and 2d. Each of the drum cleaning units 11a, 11b, 11c, and 11d removes toner and adhering matter remaining on the surfaces of the photosensitive drums 2a, 2b, 2c, and 2d, and conveys the removed toner to a predetermined recovery mechanism. , Collect.

  The secondary transfer roller 8 secondarily transfers the toner image primarily transferred to the intermediate transfer belt 7 onto the paper T. A secondary transfer bias for transferring the toner image formed on the intermediate transfer belt 7 to the paper T is applied to the secondary transfer roller 8 by a voltage application unit (not shown).

  The secondary transfer roller 8 is brought into contact with and separated from the intermediate transfer belt 7. Specifically, the secondary transfer roller 8 is configured to be movable between a contact position where the secondary transfer roller 8 is in contact with the intermediate transfer belt 7 and a separation position (separated state) that is separated from the intermediate transfer belt 7. Specifically, the secondary transfer roller 8 is moved to the contact position when the toner image primarily transferred onto the surface of the intermediate transfer belt 7 is secondarily transferred to the paper T, and is separated in other cases. It is moved to the position (separated state).

A counter roller 18 is disposed on the side of the intermediate transfer belt 7 that faces the secondary transfer roller 8. A predetermined portion of the intermediate transfer belt 7 is sandwiched between the secondary transfer roller 8 and the opposing roller 18.
Then, the paper T is pressed against the outer surface of the intermediate transfer belt 7 (the surface on which the image is primarily transferred). A secondary transfer nip N <b> 2 is formed between the secondary transfer roller 8 and the counter roller 18. The toner image primarily transferred to the intermediate transfer belt 7 is secondarily transferred to the paper T in the secondary transfer nip N2.

  The fixing unit 9 melts and fixes each color toner constituting the toner image secondarily transferred to the paper T. The fixing unit 9 includes a heating roller 9a heated by a heater and a pressure roller 9b pressed against the heating roller 9a. The heating roller 9a and the pressure roller 9b convey the paper T onto which the toner image is secondarily transferred so as to sandwich the paper T. By transporting the paper T so as to be sandwiched between the heating roller 9a and the pressure roller 9b, the toner transferred onto the paper T is melted and fixed.

<Feeding / Discharging Unit KH>
Next, the paper supply / discharge unit KH will be described.
In the lower part of the apparatus main body M, two paper feed cassettes 52 for storing paper T are arranged up and down. The paper feed cassette 52 is configured to be pulled out from the housing of the apparatus main body M in the horizontal direction. In the paper feed cassette 52, a placement plate 60 on which the paper T is placed is disposed. In the paper feed cassette 52, the paper T is stored in a state of being stacked on the placement plate 60. The paper T placed on the placement plate 60 is sent out to the transport path L by the cassette paper feed unit 51 arranged at the end of the paper feed cassette 52 on the paper feed direction F1 side. The cassette paper feed unit 51 includes a double feed prevention mechanism including a forward feed roller 61 for taking out the paper T on the placement plate 60 and a paper feed roller pair 63 for feeding the paper T to the transport path L one by one. Prepare.

  A manual paper feed unit 64 is provided on the right side surface of the apparatus main body M (the side surface in the direction opposite to the paper feed direction F1). The manual paper feed unit 64 is provided mainly for supplying a paper T having a size different from that of the paper T set in the paper feed cassette 52 to the apparatus main body M. The manual paper feed unit 64 includes a manual feed tray 65 that forms a part of the apparatus main body M in the closed state, and a paper feed roller 66. The manual feed tray 65 has a lower end attached to the vicinity of the paper feed roller 66 so as to be rotatable (openable and closable). The paper T is placed on the open manual feed tray 65. The manual paper feed unit 64 feeds the paper T placed on the open manual feed tray 65 to the manual feed path La.

A first paper discharge unit 50 a and a second paper discharge unit 50 b are provided on the upper side of the apparatus main body M. The first paper discharge unit 50a and the second paper discharge unit 50b discharge the paper T to the outside of the apparatus main body M.
Details of the first paper discharge unit 50a and the second paper discharge unit 50b will be described later.

  The conveyance path L for conveying the paper T includes a first conveyance path L1 from the cassette paper feeding unit 51 to the secondary transfer roller 8, a second conveyance path L2 from the secondary transfer roller 8 to the fixing unit 9, and a fixing unit. 9 conveys the third conveyance path L3 from the first paper discharge section 50a, the manual conveyance path La that joins the paper supplied from the manual sheet feeding section 64 to the first conveyance path L1, and the third conveyance path L3. A return conveyance path Lb that reverses the sheet T and returns it to the first conveyance path L1 and a post-processing conveyance path Lc that conveys a sheet conveyed on the third conveyance path L3 to a post-processing device (not shown) are provided.

Moreover, the 1st junction part P1 and the 2nd junction part P2 are provided in the middle of the 1st conveyance path L1. A first branch portion Q1 is provided in the middle of the third transport path L3.
The first joining part P1 is a joining part where the manual feed path La joins the first transport path L1. The second junction P2 is a junction where the return conveyance path Lb merges with the first conveyance path L1.
The first branch portion Q1 is a branch portion where the post-processing transport path Lc branches from the third transport path L3. A rectifying member 58 is provided in the first branch portion Q1. The rectifying member 58 rectifies the transport direction of the paper T carried out from the fixing unit 9 to the third transport path L3 toward the first paper discharge section 50a or the post-processing transport path Lc toward the second paper discharge section 50b ( Switch).

  In the middle of the first transport path L1 (specifically, between the second joining portion P2 and the secondary transfer roller 8), a sensor for detecting the paper T and correction of the skew (oblique paper feeding) of the paper T In addition, a registration roller pair 80 for adjusting the timing with the toner image is disposed. The sensor is disposed immediately before (on the upstream side) the registration roller pair 80 in the transport direction of the paper T. The registration roller pair 80 conveys the paper T by performing the above-described correction and timing adjustment based on the detection signal information from the sensor.

  The return conveyance path Lb is a conveyance path that is provided so that the opposite surface (non-printing surface) to the surface that has already been printed faces the photosensitive drum 2 when performing duplex printing on the paper T. According to the return transport path Lb, the paper T transported from the first branching section Q1 to the paper discharge section 50 is turned upside down and returned to the first transport path L1 and arranged upstream of the secondary transfer roller 8. It can be conveyed to the upstream side of the pair of registration rollers 80. A predetermined toner image is transferred onto the non-printing surface by the photosensitive drum 2 on the paper T that has been turned upside down by the return conveyance path Lb.

  A first paper discharge unit 50a is formed at the end of the third transport path L3. The first paper discharge unit 50 a is disposed on the upper side of the apparatus main body M. The first paper discharge unit 50a is open toward the right side of the apparatus main body M (the direction opposite to the paper feed direction F1 and the manual paper feed unit 64). The first paper discharge unit 50a discharges the paper T transported through the third transport path L3 to the outside of the apparatus main body M.

  On the opening side of the first paper discharge section 50a, a paper discharge stacking section M1 is formed. The paper discharge stacking unit M1 is formed on the upper surface (outer surface) of the apparatus main body M. The paper discharge stacking unit M1 is a part formed by the upper surface of the apparatus main body M being depressed downward. The bottom surface of the paper discharge stacking unit M1 constitutes a part of the top surface of the apparatus main body M. In the paper discharge stacking unit M1, sheets T onto which a predetermined image has been transferred and discharged from the first paper discharge unit 50a are stacked and stacked.

A second paper discharge unit 50b is formed at the end of the post-processing conveyance path Lc. The second paper discharge unit 50b is disposed on the upper side of the apparatus main body M. The second paper discharge unit 50b opens toward the left side of the apparatus main body M (the paper feed direction F1 side, the side to which the post-processing device is connected). The second paper discharge unit 50b discharges the paper T conveyed through the post-processing conveyance path Lc to the outside of the apparatus main body M.
A post-processing device (not shown) is connected to the opening side of the second paper discharge unit 50b. The post-processing device performs post-processing (stapling, punching, etc.) of paper ejected from the image forming apparatus (copy machine 1).
A paper detection sensor is disposed at a predetermined position on each conveyance path.

Next, a paper jam (JAM) in the main transport path L1 to L3 (the first transport path L1, the second transport path L2, and the third transport path L3 are collectively referred to as “main transport path” hereinafter) and the return transport path Lb. A structure for eliminating the problem will be briefly described.
On the left side of the apparatus main body M (the paper feeding direction F1 side), the main transport paths L1 to L3 and the return transport path Lb are arranged in parallel so as to mainly extend in the vertical direction. A cover body 40 is provided on the left side surface of the apparatus main body M (the sheet feeding direction F1 side) so as to form a part of the side surface of the apparatus main body M. The cover body 40 is connected to the apparatus main body M via a fulcrum shaft 43 at the lower end thereof. The fulcrum shaft 43 is disposed along the direction in which the axial direction crosses the main transport paths L1 to L3 and the return transport path Lb. The cover body 40 is configured to be rotatable between a closed position (position shown in FIG. 1) and an open position (not shown) with the fulcrum shaft 43 as a center.

  The cover body 40 includes a first cover portion 41 that is rotatably connected to the apparatus main body M by a fulcrum shaft 43, and a second cover portion 42 that is rotatably connected to the apparatus main body M by the same fulcrum shaft 43. It consists of and. The second cover portion 42 is located on the outer side (side surface side) of the apparatus main body M than the first cover portion 41. In FIG. 1, the hatched portion with the lower right broken line is the first cover portion 41, and the hatched portion with the upper right broken line is the second cover portion 42.

In the state where the cover body 40 is located at the closed position, the outer surface side of the first cover portion 41 forms a part of the outer surface (side surface) of the apparatus main body M.
Further, in the state where the cover body 40 is located at the closed position, the inner surface side (the apparatus main body M side) of the second cover portion 42 forms a part of the main transport paths L1 to L3.
Further, in a state where the cover body 40 is located at the closed position, the inner surface side of the first cover portion 41 and the outer surface side of the second cover portion 42 form at least a part of the return conveyance path Lb. That is, the return conveyance path Lb is formed between the first cover part 41 and the second cover part 42.

  The copying machine 1 of the present embodiment includes the cover body 40 having such a configuration, so that when a paper jam (JAM) occurs in the main transport paths L1 to L3, the cover body 40 is closed as shown in FIG. By rotating from the position to an open position (not shown) to open the main transport paths L1 to L3, it is possible to process paper jammed in the main transport paths L1 to L3. On the other hand, when a paper jam occurs in the return conveyance path Lb, the cover body 40 is rotated to the open position, and then the second cover portion 42 is moved around the fulcrum shaft 43 to the apparatus main body M side (paper feeding direction F1). The paper that is jammed in the return conveyance path Lb can be processed by rotating the reverse conveyance path Lb to open the return conveyance path Lb.

<Pressing device 100>
Next, the pressing device 100 will be described. FIG. 7 illustrates the shape and positional relationship between the first elliptical gear 134 that is the first rotation transmission body of the pressing device 100 of FIG. 4, the second elliptical gear 138 that is the second rotation transmission body, and the cam plate 141. FIG. FIG. 8 is a graph showing a change in the rotational speed ratio between the first elliptical gear 134 of the first rotation transmission body and the second elliptical gear 138 of the second rotation transmission body shown in FIG. FIG. 9 is an enlarged perspective view for explaining the operation of the pressing device 100 shown in FIG. FIG. 10 is an enlarged perspective view for explaining the operation of the pressing device 100 subsequent to FIG. 9.

  As shown in FIGS. 2 and 3, the pressing device 100 includes a pressing force applying mechanism 150, an approaching member displacement mechanism 120, and a displacement output unit 160. The pressing device 100 supports the counter transfer roller 18 side of the intermediate transfer belt holding frame K so that it can be displaced upward in the direction of the arrow Z.

  As shown in FIGS. 3 and 4, the pressing force applying mechanism 150 opposes the intermediate transfer belt holding frame K so that the opposing roller 18 side of the intermediate transfer belt holding frame K is displaced downward in the direction of the arrow Z. The end on the roller 18 side is urged. Specifically, the pressing force application mechanism 150 is formed of a spring. In other words, the spring that has been in the natural length state is located at the position where the photosensitive drums (first members) 2a, 2b, and 2c and the intermediate transfer belt holding frame (second member) K are in the separated state (arrows). In accordance with the displacement in the upward direction in the Z direction), it is deflected and compressed. Accordingly, the reaction force corresponding to the deflection dimension of the spring acts on the end of the intermediate transfer belt holding frame K on the side of the facing roller 18. Therefore, the photosensitive drums (first members) 2a, 2b, and 2c and the intermediate transfer belt holding frame (second member) K are displaced from the approaching position to the separated position (upward in the direction of arrow Z). As a result, the pressing force that presses the end of the intermediate transfer belt holding frame K on the opposite roller 18 side increases. The spring is, for example, a coil spring. In the case of a coil spring, the coil spring is inserted into a column 144 formed on the intermediate transfer belt holding frame K so that the coil spring does not fall down.

  The displacement output unit 160 includes a motor 162 and a worm gear 172. The motor 162 is attached to the apparatus main body M so as not to move. The motor 162 rotates the output shaft 164 forward or backward based on a signal from a control unit (not shown). The worm gear 172 is attached to the output shaft 164 of the motor 162 in a relatively non-rotatable manner.

The approaching member displacement mechanism 120 includes a first gear portion 132, a second gear portion 136, and a rotation / linear motion conversion portion 140. The first gear part 132, the second elliptical gear 138, and the rotation / linear motion conversion part 140 are attached to the apparatus main body M.
The first gear portion 132 includes a worm wheel 174 that meshes with the worm gear 172, and a first elliptical gear (first rotation transmission body) 134 that is relatively non-rotatably coupled to the worm wheel 174.
The second gear portion 136 includes a second elliptic gear (second rotation transmission body) 138 that meshes with the first elliptic gear 134, and an output shaft 176 that is relatively non-rotatably coupled to the second elliptic gear 138. Prepare.

As shown in FIG. 7, the 1st elliptical gear 134 which is a 1st rotation transmission body is an elliptical gear whose pitch circle is non-circular. Therefore, the 1st elliptical gear 134 has the structure of the 1st non-circular tooth part whose pitch circle is non-circular.
The second elliptical gear 138 as the second rotation transmission body is also an elliptical gear whose pitch circle is non-circular. Therefore, the second elliptical gear 138 has a configuration of a second non-circular tooth portion whose pitch circle is non-circular.

  The first elliptical gear 134 and the second elliptical gear 138 have substantially the same shape. The first elliptical gear 134 and the second elliptical gear 138 are meshed so that the major axis of the first elliptical gear 134 and the minor axis of the second elliptical gear 138 are in contact with each other.

Therefore, as shown in FIG. 8, the rotational speed ratio of the second elliptical gear 138 to the first elliptical gear 134 may be greater than 1 depending on the rotational angle of the first elliptical gear 134, as indicated by the line Ls. It gets smaller.
When the rotational speed ratio of the second elliptical gear 138 to the first elliptical gear 134 is greater than 1 (for example, point S1 in FIG. 8), the rotational speed of the second elliptical gear 138 is higher than the rotational speed of the first elliptical gear 134. As a result, the rotational force (torque) of the second elliptical gear 138 becomes smaller than the rotational force (torque) of the first elliptical gear 134.

When the rotational speed ratio of the second elliptical gear 138 to the first elliptical gear 134 is the same as 1 (for example, point S2 in FIG. 8), the rotational speed of the second elliptical gear 138 becomes equal to the rotational speed of the first elliptical gear 134. The rotational force (torque) of the second elliptical gear 138 is the same as the rotational force (torque) of the first elliptical gear 134.
When the rotational speed ratio of the second elliptical gear 138 to the first elliptical gear 134 is smaller than 1 (for example, point S3 in FIG. 8), the rotational speed of the second elliptical gear 138 is higher than the rotational speed of the first elliptical gear 134. As a result, the rotational force (torque) of the second elliptical gear 138 becomes larger than the rotational force (torque) of the first elliptical gear 134.

As shown in FIGS. 4 and 7, the rotation / linear motion conversion unit 140 includes a cam plate 141 attached to the output shaft 176 so as not to rotate relatively. The cam plate 141 is disposed below the intermediate transfer belt holding frame K on the opposite roller 18 side of the intermediate transfer belt holding frame K.
Since the output shaft 176 is rotatably supported by the apparatus main body M, the cam plate 141 is rotatably supported by the apparatus main body M.
As shown in FIG. 7, the side surface 142 of the cam plate 141 has a curved surface in which the side surface distance between the output shaft 176 and the side surface 142 increases as it goes in the circumferential direction about the output shaft 176. In other words, the side surface distance R1 between the point C1 located on the side surface 142 and the center C of the output shaft 176, the point C2 located on the side surface 142 counterclockwise from the point C1, and the center C of the output shaft 176 Is compared with the side surface distance R2, the side surface distance R2 is longer than the side surface distance R1.
Specifically, when the cam plate 141 is viewed from the direction in which the output shaft 176 extends, the cam plate 141 has an arc shape, and the output shaft 176 is in an eccentric position with respect to the center of the arc shape of the cam plate 141. .

  The cam plate 141 is disposed such that the side surface 142 of the cam plate 141 is in contact with the lower surface of the intermediate transfer belt holding frame K in the direction of arrow Z.

As shown in FIG. 7, when the vicinity of the point C0 at which the side surface distance becomes small comes into contact with the lower plane of the intermediate transfer belt holding frame K, the cam plate 141 has the major axis of the first elliptical gear 134. The output shaft 176 is assembled so that the minor axis of the second elliptical gear 138 is in contact therewith.
Further, when the vicinity of the point C2 where the side distance is large in the cam plate 141 comes into contact with the lower surface of the intermediate transfer belt holding frame K, the cam plate 141 has the short diameter of the first elliptical gear 134 and the second diameter. The elliptical gear 138 is assembled to the output shaft 176 so as to be in contact with the major axis of the elliptical gear 138 (see FIG. 8).
The angle between the imaginary line extending from the center C toward the point C0 and the imaginary line extending from the center C toward the point C2 is an angle formed by the major axis and the minor axis of the first elliptical gear 134 (specifically, Is the same as 90 degrees).

  Therefore, the cam plate 141 moves the opposite roller 18 side of the intermediate transfer belt holding frame K while the side surface 142 of the cam plate 141 contacts the lower surface of the intermediate transfer belt holding frame K as the cam plate 141 rotates. It is configured to lift upward.

<Operation of the pressing device 100>
Next, the operation of the pressing device 100 will be described with reference to an example in which color printing is performed after the copying machine 1 performs monochrome printing.
(Color printing)
First, the case where the copier 1 performs color printing will be described. The pressing device 100 brings the primary transfer rollers 37a, 37b, and 37c through the intermediate transfer belt holding frame K into an approaching state close to the photosensitive drums 2a, 2b, and 2c.
Specifically, as shown in FIGS. 4 and 6, the first elliptical gear 134 and the second elliptical gear 138 are such that the major axis of the first elliptical gear 134 and the minor axis of the second elliptical gear 138 are in contact with each other. Are meshing. At this time, since the side surface distance of the side surface 142 of the cam plate 141 at the position where the side surface 142 of the cam plate 141 is closest to the intermediate transfer belt holding frame K is short, the intermediate transfer belt holding frame K is held by the intermediate transfer belt holding frame K. Along with the weight of the frame K, the pressing force applying mechanism 150 lowers in the direction of the arrow Z due to the urging force.

  When the intermediate transfer belt holding frame K is lowered in the direction of the arrow Z, the primary transfer rollers 37a, 37b, and 37c are also lowered. Thus, primary transfer nips N1a, N1b, N1c, and N1d are formed between the photosensitive drums 2a, 2b, 2c, and 2d and the primary transfer rollers 37a, 37b, 37c, and 37d, respectively. In the primary transfer nips N1a, N1b, N1c, and N1d, the respective color toner images developed on the photosensitive drums 2a, 2b, 2c, and 2d are sequentially transferred to the intermediate transfer belt 7. As a result, a color toner image is formed on the intermediate transfer belt 7 and color printing is performed.

(Black and white printing)
Next, a case where the copier 1 performs monochrome printing will be described. The pressing device 100 operates the displacement output unit 160 to place the primary transfer rollers 37a, 37b, and 37c away from the photosensitive drums 2a, 2b, and 2c via the intermediate transfer belt holding frame K.
The operation of the displacement output unit 160 is started when the pressing device 100 is in the state shown in FIG.
When the displacement output unit 160 operates, the output shaft 164 of the motor 162 rotates, and the first elliptical gear 134 rotates via the worm gear 172 and the worm wheel 174.
At this time, the major axis of the first elliptical gear 134 and the minor axis of the second elliptical gear 138 are in contact with each other.
As the first elliptical gear 134 rotates, the rotation ratio of the second elliptical gear 138 to the first elliptical gear 134 is the same as 1 from a state where the rotational ratio is greater than 1 (see point S1 in FIGS. 4 and 6). Through the state (see point S2 in FIGS. 7 and 6), the state becomes smaller than 1 (see point S3 in FIGS. 8 and 6). That is, the transmission ratio of the rotational force (torque) of the second elliptical gear 138 to the first elliptical gear 134 changes from a state smaller than 1 to a state larger than 1 through the same state as 1.

  As the first elliptical gear 134 rotates, the cam plate 141 rotates. When the cam plate 141 rotates, the side surface 142 comes into contact with the lower surface of the intermediate transfer belt holding frame K on the opposite roller 18 side. Further, as shown in FIGS. 7 and 8, when the first elliptical gear 134 rotates, the side surface 142 of the cam plate 141 pushes up the lower surface of the intermediate transfer belt holding frame K, and the primary transfer rollers 37a, 37b, and 37c are the photosensitive members. It will be in the separated state spaced apart from drum 2a, 2b, 2c.

  Therefore, the primary transfer nips N1a, N1b, and N1c that are formed between the photosensitive drums 2a, 2b, and 2c and the primary transfer rollers 37a, 37b, and 37c, respectively, are not formed. Accordingly, only the black toner image developed on the photosensitive drum 2d is transferred to the intermediate transfer belt 7 in the primary transfer nip N1d. As a result, a black and white toner image is formed on the intermediate transfer belt 7 and black and white printing is performed.

According to the copier 1 and the pressing device 100 of the present embodiment, for example, the following effects are exhibited.
According to the pressing device 100 of the copier 1 of the present embodiment, the intermediate transfer belt holding frame that is disposed so as to be displaceable in the approaching state or the separating state that is close to the photosensitive drums (first members) 2a, 2b, and 2c. (Second member) The second member is pressed so as to be in a separated state. The pressing device 100 displaces the pressing force applying mechanism 150 that presses the intermediate transfer belt holding frame (second member) K so as to be in the approaching state, and the intermediate transfer belt holding frame (second member) K from the approaching state to the separated state. An approaching member displacement mechanism 120 to be moved, and a displacement output unit 160 for operating the approaching member displacement mechanism 120. The approaching member displacement mechanism 120 rotates the first elliptical gear (first rotation transmission body) 134 that receives the transmission of the rotational force (torque) of the displacement output unit 160 and the first elliptical gear (first rotation transmission body) 134. The rotational movement of the second elliptical gear (second rotational transmission body) 138 that receives the transmission of force (torque) and the second elliptical gear (second rotational transmission body) 138 is converted into a linear motion, and the intermediate transfer belt holding frame ( And a rotation / linear motion conversion unit 140 that puts K in a separated state. The second elliptical gear (second rotation transmission body) 138 has a reduction ratio from the first elliptical gear 134 to the second elliptical gear (second rotation transmission body) 138 as the first elliptical gear 134 rotates. The first elliptical gear 134 is arranged so that the photosensitive drums (first members) 2a, 2b, and 2c and the intermediate transfer belt holding frame (second member) K are displaced from the separated state to the approaching state so as to decrease. It receives the torque (torque) transmitted.

  That is, the second elliptical gear (second rotation transmission body) 138 is changed from the first elliptical gear (first rotation transmission body) 134 to the first elliptical gear (first rotation transmission body) 134 as the first elliptical gear (first rotation transmission body) 134 rotates. The rotational force (torque) of the first elliptical gear (first rotation transmission body) 134 is transmitted so that the reduction ratio to the two elliptical gear (second rotation transmission body) 138 is reduced. As the reduction ratio decreases, the transmitted rotational force (torque) increases, so that the second elliptical gear (second rotational transmission body) 138 as the first elliptical gear (first rotational transmission body) 134 rotates. Receives transmission of a large rotational force (torque). For this reason, the pressing device 100 that presses the intermediate transfer belt holding frame (second member) K, which is disposed so as to be displaceable in the approaching state or the separating state, into the separating state, has an intermediate transfer belt holding frame (second member) K. In the operation of shifting the position from the approaching position to the separating position, the motor (displacement output unit) 160 is less likely to be overloaded.

  When the photosensitive drums (first members) 2a, 2b, 2c and the intermediate transfer belt holding frame (second member) K are in the approaching position, the first elliptical gear (first rotation transmission body) 134 is provided. The rotation speed ratio of the second elliptical gear (second rotation transmission body) 138 with respect to is large, and the rotation speed ratio is small when it is in the separated state. For this reason, when the intermediate transfer belt holding frame (second member) K is displaced from the approaching position to the separating position, the reduction ratio is gradually increased (the rotational speed is gradually decreased). Therefore, in the state where the intermediate transfer belt holding frame (second member) K is displaced from the approaching position to the separating position, the rotation speed of the second elliptical gear (second rotation transmitting body) 138 is fast. Therefore, the intermediate transfer belt holding frame (second member) K and the photosensitive drums (first member) 2a, 2b, and 2c can be greatly separated at an early stage.

Further, according to the pressing device 100 of the image forming apparatus 1 of the present embodiment, the first elliptical gear (first rotation transmission body) 138 has the first noncircular tooth portion whose pitch circle is noncircular, and the second The elliptical gear (second rotation transmission body) has a second non-circular tooth portion which meshes with the first non-circular tooth portion and whose pitch circle is non-circular.
For this reason, the rotational force (torque) is reliably transmitted between the first elliptical gear (first rotation transmission body) and the second elliptical gear (second rotation transmission body).

  Further, the pressing force applying mechanism 150 according to the present embodiment is configured so that the photosensitive drums (first members) 2a, 2b, and 2c and the intermediate transfer belt holding frame (second member) K are moved from the approaching position to the separated position. Along with the displacement, there is a spring that increases the pressing force that presses the intermediate transfer belt holding frame (second member) K against the photosensitive drums (first member) 2a, 2b, 2c.

As described above, the urging force of the pressing force applying mechanism 150 increases with the displacement from the approaching position to the separation position. Further, according to the pressing device 100 of the image forming apparatus 1, the rotational speed ratio increases with the displacement from the approaching position to the separating position.
Therefore, since the load torque acting on the output shaft 176 can be made constant, it is possible to prevent breakage of the gear, removal of the gear press-fitted into the output shaft 176, and the like.
Further, since the load torque acting on the output shaft 176 is constant, the wear of the motor bearing and the brush of the brushed motor 162 can be reduced, and the life of the motor 162 is extended.
Furthermore, when the motor 162 uses a DC motor, the current value can be kept constant, so that a rapid change in motor temperature, reduction in power consumption, and the like can be expected.

<Copy machine 1a>
Next, as shown in FIGS. 11 and 12, the copier 1a will be described.
FIG. 11 is a perspective view for explaining the positional relationship between the heating roller 9a and the pressure roller 9b in the approaching state of the fixing unit 9 of the copying machine 1a as the second embodiment of the present invention. FIG. 12 is a perspective view for explaining the positional relationship between the heating roller 9a and the pressure roller 9b in the separated state of the fixing unit 9 of the copier 1a shown in FIG.

  The copying machine 1a biases the pressure roller 9b of the fixing unit 9 so as to approach the heating roller 9a instead of the intermediate transfer belt holding frame K biased by the pressing force applying mechanism 150 in the copying machine 1. As such, it has changed. Accordingly, the heating roller 9a is supported by the apparatus main body M as a first member, and the pressure roller 9b is supported by the apparatus main body M as a second member so as to be displaceable between an approaching position and a separating position with respect to the heating roller 9a. Has been.

As shown in FIG. 11, when the pressing roller 9b is in an approaching state where the pressure roller 9b is in contact with the heating roller 9a, the pressing device 100 uses the short diameter of the first elliptical gear 134 and the second elliptical gear as shown in FIG. The major axis of 138 is in contact.
As shown in FIG. 12, when the pressure roller 9b is separated from the heating roller 9a, as shown in FIG. 4, the pressing device 100 has the long diameter of the first elliptical gear 134 and the second elliptical gear 138. Is in contact with the minor axis.

<Other embodiments>
As mentioned above, although preferred embodiment was described, this invention can be implemented with a various form, without being limited to embodiment mentioned above. For example, in the present embodiment, the copying machine 1 is described as an image forming apparatus, but the present invention is not limited to this, and a printer, a facsimile, a complex machine thereof, or the like may be used.

Although the 1st rotation transmission body and the 2nd rotation transmission body were explained as the 1st elliptical gear 134 and the 2nd elliptical gear 138, respectively, it is not limited to this. The first rotation transmission body and the second rotation transmission body are configured such that a reduction ratio from the first rotation transmission body to the second rotation transmission body decreases as the first rotation transmission body rotates. That's fine. Specifically, the first rotation transmission body and the second rotation transmission body may be non-circular gears other than elliptical gears.
Moreover, although this embodiment demonstrated the 1st rotation transmission body and the 2nd rotation transmission body as the elliptical gearwheel by which the tooth | gear was formed in the perimeter, it is not limited to this. The first elliptical gear 134 and the second elliptical gear 138 may be partial elliptical gears in which teeth are formed only on part of the circumference.

Although the displacement output unit 160 has been described as the motor 162, the displacement output unit 160 is not limited thereto, and is a piston crank mechanism including a pressing force applying mechanism such as a cylinder and a link mechanism that converts the reciprocating motion of the pressing force applying mechanism into a rotational motion. There may be.
The pressing device 100 presses the intermediate transfer belt holding frame K, but is not limited thereto. For example, the pressing device 100 includes the registration roller pair 80, the secondary transfer roller 8 and the opposing roller 18, the forward feed roller 61, and the paper feed roller pair 63, and the position and the distance between the pair of rollers approaching each other. It may be used to displace the state position.
The pressing force applying mechanism 150 has been described as a coil spring, but is not limited to this, and may be a tension spring, a leaf spring, or a disc spring.
The sheet is not limited to paper, and may be a film sheet, for example.

  DESCRIPTION OF SYMBOLS 1, 1a ... Copy machine (image forming apparatus), 2a, 2b, 2c ... Photosensitive drum (1st member), 7 ... Intermediate transfer belt, 100 ... Pressing device, 120 ... Approaching member displacement mechanism, 132 …… First gear portion, 134 …… First elliptic gear (first rotation transmission body), 136 …… Second gear portion, 138 …… Second elliptic gear (second rotation transmission body), 140 …… Rotation Linear motion conversion unit, 141 ... cam plate, 142 ... side surface of cam plate, 150 ... pressing force applying mechanism, 160 ... output unit for displacement, 162 ... motor, 164 ... output shaft of motor, 172 ... ... Worm gear, 174 ... Worm wheel, 176 ... Output shaft, GK ... Image forming section, K ... Intermediate transfer belt holding frame (second member), T ... Paper (sheet)

Claims (4)

A pressing device that presses a second member disposed so as to be displaceable in an approaching state or a spaced apart state approaching the first member so as to be in the separated state,
A pressing force application mechanism that presses the second member to the close state;
An approach member displacement mechanism for displacing the second member from the approach state to the separated state;
A displacement output section for operating the approaching member displacement mechanism,
The approach member displacement mechanism is:
A first rotation transmission body that receives transmission of the rotational force of the displacement output section;
A second rotation transmission body that receives transmission of the rotational force of the first rotation transmission body;
A rotation / linear motion conversion unit that converts the rotational motion of the second rotation transmission body into a reciprocating motion and places the second member in the separated state;
The second rotation transmission body is configured so that a reduction ratio from the first rotation transmission body to the second rotation transmission body decreases as the first rotation transmission body rotates, and the first rotation transmission body A pressing device of an image forming apparatus that receives transmission of a rotational force of the first rotation transmission body so that a member and the second member are displaced from the separated state to the approaching state. The first rotation transmission body has a first non-circular tooth portion whose pitch circle is non-circular,
2. The pressing device for an image forming apparatus according to claim 1, wherein the second rotation transmission body includes a second non-circular tooth portion that meshes with the first non-circular tooth portion and has a non-circular pitch circle.   The pressing force applying mechanism is configured to press the second member against the first member as the first member and the second member are displaced from the approaching position to the separated state. The pressing device for an image forming apparatus according to claim 1, further comprising a spring whose pressure increases.   An image forming apparatus comprising: an image forming unit that forms an image on a sheet; and the pressing device according to claim 1.

Images