JP5364633B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus.

  Conventionally, in an image forming apparatus such as a copying machine, a printer, a facsimile, or a multi-function machine having a plurality of these functions, when the image forming apparatus is a full color type, yellow (Y), magenta (M) , Cyan (C), and black (BK), a plurality of photoconductors each having a drum corresponding to each color are prepared. A predetermined electrostatic latent image is formed on the peripheral surface of each photoconductor using a laser scanning unit, and a toner image of each color is formed on the peripheral surface of each photoconductor by the supplied toner of each color. Each is generated. The toner images of the respective colors generated on the peripheral surfaces of the respective photoconductors are sequentially superimposed and transferred onto a transfer belt composed of an endless belt that is driven to rotate, whereby a color image is synthesized on the transfer belt. Next, the color image synthesized on the transfer belt is transferred to a recording medium such as recording paper, and then subjected to a fixing process by being pressurized and heated by a fixing device (see Patent Document 1).

The fixing device fixes a toner image formed on a recording paper, and includes a fixing roller for applying heat to the recording paper and a pressure roller for pressing the recording paper against the fixing roller. . These fixing roller and pressure roller are provided in a unit case forming a unit of the fixing device.
In the unit case, in addition to the fixing roller and the pressure roller, a conveyance roller that applies a conveyance force to the recording paper after fixing is provided. The conveying roller includes a driving roller and a driven roller that is pressed and driven by the driving roller.
In the fixing device having the above configuration, when the recording paper holding the toner image is positioned between the fixing roller and the pressure roller, the recording paper is heated and pressed to fix the toner, and the conveyance roller rotates. Is conveyed to the discharge tray side.

JP 2008-1000081 A

  However, in the image forming apparatus provided with the conventional fixing device, when a paper jam or a so-called jam occurs in the fixing device, it is necessary to pull out the jammed paper from the fixing device. Here, if the jam paper has a strong gripping force of a conveyance roller including a driving roller and a driven roller, the jam paper cannot be pulled out easily.

  SUMMARY An advantage of some aspects of the invention is that it is possible to easily remove jammed paper from a fixing device in an image forming apparatus.

  The present invention adopts the following configuration as means for solving the above-described problems.

  According to a first aspect of the present invention, there is provided a fixing device having a pair of conveying rollers that sandwich and convey a recording medium, and a conveying device that conveys the recording medium and has a detachable portion that is detachable from a main body on which the fixing device is mounted. An image forming apparatus including a unit, wherein when the detachable portion is attached to the main body, one of the transport rollers constituting the transport roller pair is urged against the other transport roller. A configuration in which an urging means is provided is adopted.

  According to a second invention, in the first invention, the urging means is provided in a fixing portion and a shaft support portion that supports the rotation shaft of the transport roller, and when the detachable portion is attached to the main body. A contact portion that is in contact with the pressing portion of the detachable portion from a direction orthogonal to the rotation axis of the transport roller, and is supported so as to be movable in the contact direction with respect to the pressing portion; the contact portion; and A configuration is adopted in which an elastic member interposed between the shaft support portion and the shaft support portion is provided.

  According to a third invention, in the first or second invention, a plurality of the urging means are provided, and these urging means are arranged symmetrically with respect to the center in the extending direction of the rotation shaft of the conveying roller. Adopt the configuration that.

  According to a fourth invention, in any one of the first to third inventions, the urging means is arranged so as to avoid an area overlapping with a passing area of the recording medium in the extending direction of the rotation shaft of the transport roller. Adopt a configuration that

  According to a fifth invention, in any one of the first to fourth inventions, the attachment / detachment portion constitutes a part of an inversion path for inversion of the recording medium, and the fixing device is detached when detached from the main body. A configuration is adopted in which the upper region is opened.

  According to the present invention, when the fixing device is mounted on the main body, it is provided with a biasing unit that biases one of the transport rollers constituting the pair of transport rollers with respect to the other transport roller. For this reason, it is possible to secure a conveyance force when the fixing device is mounted on the main body, and it is possible to easily pull out jammed paper because the biasing force is weakened when the fixing device is detached from the main body.

1 is a cross-sectional view illustrating a schematic configuration of a copying machine to which a fixing device according to an embodiment of the present invention is applied. FIG. 4 is a plan view including a driving roller and a driven roller of the fixing device according to the embodiment of the present invention. FIG. 3 is a cross-sectional view including a driving roller and a driven roller of the fixing device according to the embodiment of the present invention. FIG. 6 is a perspective view including another example of a driving roller and a driven roller of a fixing device according to an embodiment of the present invention. FIG. 4 is a plan view of the fixing device according to the embodiment of the present invention when a detachable portion is detached. FIG. 3 is a cross-sectional view of the fixing device according to the embodiment of the present invention when a detachable portion is detached.

  Hereinafter, an embodiment of an image forming apparatus including a fixing device according to the present invention will be described with reference to the drawings. In the following drawings, the scale of each member is appropriately changed in order to make each member a recognizable size. In the following description, a copying machine will be described as an example of the image forming apparatus of the present invention.

  FIG. 1 is a perspective view of an electrophotographic full-color copying machine P. This copying machine P is based on an image reading unit 1 that reads an image of a document and read image data, as in a known copying machine. And a printing unit 2 that performs printing on recording paper (recording medium).

  The image reading unit 1 irradiates an image of a document with light and receives reflected light to read the image of the document as image data. The image reading unit 1 receives light returned from the light source device or the document that irradiates the document with light. It includes a light receiving sensor that receives light and converts it into image data.

  The printing unit 2 includes a belt unit 6, an image forming unit 7, a paper feed cassette 8, a paper feed tray 9, a secondary transfer unit 10, a fixing device 11, a paper discharge tray 12, and a conveyance path 13. And a waste toner collecting unit 14.

  The belt unit 6 transfers the toner image formed in the image forming unit 7 and conveys the transferred toner image. The belt unit 6 includes an intermediate transfer belt 61 to which the toner image is transferred from the image forming unit 7, and an intermediate transfer belt 61. The transfer belt 61 is provided with a driving roller 62 for ending and feeding endlessly, a driven roller 63, a tension roller 64, and a cleaning unit (not shown).

The intermediate transfer belt 61 is stretched around a driving roller 62, a driven roller 63, and a tension roller 64.
The drive roller 62 is connected to a drive unit having a drive source such as a motor, and rotates while applying a grip force to the intermediate transfer belt 61.
The driven roller 63 is driven to rotate following the rotational drive of the drive roller 62.
The tension roller 64 is a kind of driven roller that is driven to rotate by the rotational driving of the driving roller 62, and has a spring mechanism to apply tension to the intermediate transfer belt 61.

  A cleaning unit (not shown) is provided downstream of the drive roller 62 with respect to the intermediate transfer belt 61 and upstream of the first image forming unit 7 (yellow (Y)).

  The image forming unit 7 is provided corresponding to each color of yellow (Y), magenta (M), cyan (C), and black (BK), and forms a toner image of each color. These image forming units 7 are arranged in order from the upstream side to the downstream direction along the rotational driving direction of the intermediate transfer belt 61.

  Each image forming unit 7 includes a photoreceptor 71, a charger 72, a laser scanning unit 73, a developing device 74, a primary transfer roller 75, a cleaning device 76, a static elimination device (not shown), and the like.

  The photosensitive member 71 is formed in a cylindrical shape, and an electrostatic latent image and a toner image based on the electrostatic latent image are formed on the peripheral surface thereof. The charger 72 is disposed to face the photoconductor 71 and charges the peripheral surface of the photoconductor 71. The laser scanning unit 73 scans the circumferential surface of the charged photoreceptor 71 with laser light emitted based on the image data in the print format.

The developing device 74 develops a toner image based on the electrostatic latent image on the circumferential surface of the photoreceptor 71 by supplying toner to the circumferential surface of the photoreceptor 71.
The primary transfer roller 75 is disposed opposite to the photoreceptor 71 with the intermediate transfer belt 61 interposed therebetween, and primarily transfers the toner image developed on the photoreceptor 71 to the intermediate transfer belt 61. The cleaning device 76 removes toner remaining on the photoreceptor 71 after the primary transfer.

The paper feed cassette 8 can be pulled out with respect to the apparatus main body and accommodates recording paper (recording medium). The paper feed tray 9 is openable and closable with respect to the apparatus main body, and accommodates recording paper.
The secondary transfer unit 10 performs secondary transfer of the image formed on the intermediate transfer belt 61 to a storage medium. The secondary transfer unit 10 sandwiches the drive roller 62 that drives the intermediate transfer belt 61 and the intermediate transfer belt 61 therebetween. The drive roller 62 and the secondary transfer roller 10a are arranged to face each other.

  The fixing device 11 fixes a toner image secondarily transferred onto a recording paper (recording medium) onto the recording paper, and includes a fixing roller (heating roller) 100, a pressure roller 110, a driving roller 120, and a driven roller. The roller 130 is arranged in the unit case 140. The fixing device 11 will be described in detail later with reference to the drawings.

The transport path 13 includes a pickup roller 13 a that transports the recording paper from the paper feed cassette 8, a paper feed roller 13 b that transports the recording paper, a paper discharge roller 13 c that discharges the recording paper to the paper discharge tray 12, and the like.
In the copying machine P according to the present embodiment, as shown in FIG. 1, the conveyance unit 13 (conveyance unit) includes a reversing path 13 </ b> A for reversing the recording paper and feeding it to the fixing device 11. A part of the reversing path 13A is configured to be detachable from the main body of the copier P so that the jammed paper can be removed from the transport unit 13 when a jam occurs. Hereinafter, a detachable part of the inversion path 13A is referred to as a detachable portion 200.

As shown in FIG. 1, the detachable part 200 is attached to the main body of the copying machine P via a hinge 201, and is configured to be opened and closed around the hinge 201.
When the detaching portion 200 is opened, the reversing path 13A is opened and the upper region R of the fixing device 11 is opened, so that a later-described driving roller 120 and driven roller 130 included in the fixing device 11 are opened. The user can easily access it.
On the other hand, a pressing portion 202 is provided on the main body side of the detachable portion 200. When the detachable portion 200 is closed, cap portions 143a and 143b (contact portions), which will be described later, installed in the fixing device 11 are used. Thus, the pressing portion 202 is configured to be pressed.

  In the copying machine P having such a configuration, as described above, image data is acquired by the image reading unit 1, and color printing is performed on recording paper based on the image data by the printing unit 2.

  Hereinafter, the fixing device 11 will be described with reference to FIGS. As shown in FIG. 1, the fixing device 11 includes a fixing roller (heating roller) 100 and a pressure roller 110, a driving roller 120 and a driven roller 130, a driven roller urging mechanism 140, and a unit case 150. ing.

  The fixing roller (heating roller) 100 has a roller surface made of a heat-resistant elastic material and has a heat source disposed therein, and its axial length is perpendicular to the recording paper conveyance direction. It is formed to be slightly larger than the width in the direction. The fixing roller 100 is provided such that its axial direction is orthogonal to the recording paper conveyance direction.

  The pressure roller 110 is configured to have the same axial length as the fixing roller 100, and the roller surface is formed of a heat-resistant elastic material, like the fixing roller 100. The axial direction of the pressure roller 110 is parallel to the fixing roller 100 and is disposed so that the surfaces of both the rollers 100 and 110 are in contact with each other.

  The driving roller 120 corresponds to one of the conveying rollers of the present invention, and the support shaft 121 of the driving roller 120 is connected to a driving source (not shown) and is driven to rotate. The length in the axial direction is the same as that of the fixing roller 100 and the pressure roller 110, and the surface of the roller is formed of an elastic material having heat resistance, like the rollers 100 and 110. . The drive roller 120 is provided on the downstream side of the fixing roller 100 and the pressure roller 110 with respect to the recording paper transport direction, and the axial direction of the drive roller 120 is the recording paper transport direction. It is provided to be orthogonal.

  2 and 5, the entire shape of the drive roller 120 is formed as a single column. However, as shown in FIG. 4, the drive roller 120 is formed along the longitudinal direction of the support shaft 121. A plurality of discs having a little thickness may be arranged at predetermined intervals.

The driven roller 130 corresponds to the other conveying roller of the conveying roller pair of the present invention, and the length of the shaft 131 of the driven roller 130 in the axial center direction is the same as that of the driving roller 120, and the roller surface is As with the drive roller 120, it is made of an elastic material having heat resistance. The axial direction of the driven roller 130 is parallel to the driving roller 120 and is arranged so that the surfaces of both the rollers 120 and 130 are in contact with each other. Therefore, the driven roller 130 can be rotated by the rotational force of the driving roller 120 when in contact with the driving roller 120.
2 and 5, the entire shape of the driven roller 130 is formed as a single column. However, like the drive roller 120 shown in FIG. A plurality of discs having a little thickness may be arranged at predetermined intervals along the configuration to reduce the manufacturing cost.

  The driven roller urging mechanism 140 corresponds to the urging means of the present invention, and includes shaft support portions 141a and 141b, coil springs 142a and 142b, and cap portions 143a and 143b.

  The shaft support portions 141 a and 141 b rotatably support both ends of the support shaft 131 of the driven roller 130, and the support shaft 131 of the driven roller 130 is orthogonal to the axial direction of the support shaft 121 of the drive roller 120. It is provided so as to be movable in the direction. These shaft support portions 141a and 141b are respectively provided with flanges 144a and 144b in the center portion of the shaft portion.

  The coil springs 142a and 142b correspond to the elastic member of the present invention, and are respectively wound around shaft support portions 141a and 141b on the outer side (opposite side of the support shaft 131) of the flanges 144a and 144b.

The cap portions 143a and 143b correspond to the contact portions of the present invention, and are formed of a cylindrical body that is open on one end side, and the inner diameter thereof is the outer diameter of the flanges 144a and 144b of the shaft support portions 141a and 141b and the coil springs 142a and 142b. It is formed slightly larger.
The cap portions 143a and 143b are respectively mounted on the shaft support portions 141a and 141b around which the coil springs 142a and 142b are wound so as to incorporate the coil springs 142a and 142b. The caps 143a and 143b are provided so that the opposite sides of the caps 143a and 143b protrude slightly from the unit case 150 and are movable relative to the unit case 150.
Such cap parts 143a and 143b are pressed by the pressing part 202 provided in the detachable part 200 when the aforementioned detachable part 200 is closed.

  The unit case 150 has a space in the unit case 150 that can sufficiently accommodate the fixing roller 100, the pressure roller 110, the driving roller 120, the driven roller 130, and the driven roller urging mechanism 140.

2 and 3 show a state in which the above-described detachable portion 200 is attached to the main body of the copying machine P (a state where the detachable portion 200 is closed), and the side opposite to the opening side of the cap portions 143a and 143b is detachable. It shows a state in which the pressing force of the coil springs 142 a and 142 b is applied to the support shaft 131 of the driven roller 130 by being pressed by the pressing portion 202 of the portion 200. In this state, a strong grip force is generated between the transport roller 120 and the driven roller 130, and the recording paper transport force can be ensured.
5 and 6 show a state where the above-described detaching unit 200 is detached from the main body of the copying machine P (a state where the detaching unit 200 is opened). In this state, the side opposite to the opening side of the cap parts 143a, 143b is located away from the attaching / detaching part 200, and the pressing force of the coil springs 142a, 142b is not acting on the support shaft 131 of the driven roller 130. I'm left. Therefore, no grip force is generated between the driving roller 120 and the driven roller 130 in this state.

  In the copying machine P having the fixing device 11 having the above-described configuration, when the recording paper holding the toner image is positioned between the fixing roller 100 and the pressure roller 110, the recording paper is conveyed by the rotation of the rollers 100 and 110. In addition, the toner is fixed on the recording paper by applying heat and pressure. Then, the fixed recording paper is nipped and conveyed by the driving roller 120 and the driven roller 130 and is discharged to the paper discharge tray 12.

  On the other hand, when a jam occurs, the detaching portion 200 is detached from the main body (see FIGS. 5 and 6), and the jammed paper is pulled out. When the detaching portion 200 is detached, the cap portions 143a and 143b are separated from the detaching portion 200, and the pressing force of the coil springs 142a and 142b does not act on the support shaft 131 of the driven roller 130. Furthermore, when the detaching portion 200 is detached, the upper region R of the fixing device 11 is opened, and the user can easily access the driving roller 120 and the driven roller 130. Therefore, in this state, the jammed paper between the driving roller 120 and the driven roller 130 can be easily pulled out, and the jam can be easily eliminated. After the jam is removed, the detaching unit 200 is mounted at a predetermined position in the main body of the copying machine P without requiring a troublesome operation, and thereby the pressing force is applied to the driven roller 130 again.

Further, in the present embodiment, two (a plurality) of driven roller urging mechanisms 140 are provided, and these driven roller urging mechanisms 140 are arranged symmetrically with respect to the center in the extending direction of the driven roller 130. Yes.
For this reason, in the extending direction of the driven roller 130, the pressing force between the driving roller 120 and the driven roller 130 can be made uniform, and the occurrence of jam can be suppressed.

In the present embodiment, the driven roller urging mechanism 140 is disposed so as to avoid an area overlapping with the recording paper passage area in the extending direction of the driven roller 130.
For this reason, it is possible to prevent a large pressing force from acting locally on the recording paper, to equalize the pressing force between the driving roller 120 and the driven roller 130, and to further suppress the occurrence of a jam. can do.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to the said embodiment. Various shapes, combinations, and the like of the constituent members shown in the above-described embodiments are examples, and various modifications can be made based on design requirements and the like without departing from the gist of the present invention.

For example, in the above-described example, the case where the copying machine P is a full-color type has been described, but it may be a monochrome type.
Furthermore, in the above-described example, the coil springs 142a and 142b corresponding to the elastic member of the present invention are provided inside the unit case 150 to press the support shaft 131. However, any mechanism that presses the support shaft 131 may be used. The elastic member may be provided on the outside of the unit case 150, that is, on the detachable portion 200 side.
In the above-described example, the conveyance roller pair including the driving roller 120 and the driven roller 130 is applied to the fixing device 11 of the copying machine (image forming apparatus) P. However, the recording paper is conveyed in other parts of the image forming apparatus. You may make it provide in.

  P: copier (image forming apparatus), 11: fixing device, 13: conveying unit (conveying unit), 100: fixing roller, 110: pressure roller, 120: driving roller, 121: support Shaft, 130... Driven roller, 131... Support shaft, 140... Driven roller urging mechanism (biasing means), 141 a and 141 b. ...... Cap part (contact part), 150 ...... Unit case, 200 ...... Desorption part, 202 ...... Pressing part, R ...... Upper area of fixing device

Claims (4)

Image forming apparatus comprising: a fixing device having a pair of conveying rollers that sandwich and convey a recording medium; and a conveying unit that conveys the recording medium and has a detachable portion that is detachable from a main body on which the fixing device is mounted. A device,
An urging means for urging one of the conveying rollers constituting the pair of conveying rollers to be rotatable with respect to the other conveying roller when the detachable portion is mounted on the main body;
The fixing device includes a fixing member and a pressure member for fixing a toner image on the recording medium, and the pair of conveying rollers is disposed on the downstream side of the fixing member and the pressure member in the conveying direction of the recording medium. It has been,
The biasing means is
A shaft support portion that supports the rotation shaft of the transport roller;
Provided in the fixing device, when the detachable portion is attached to the main body, the contact portion contacts the pressing portion of the detachable portion from a direction orthogonal to the rotation axis of the transport roller, and the contact direction to the pressing portion An abutment that is movably supported;
An elastic member interposed between the contact portion and the shaft support portion;
With
The image forming apparatus according to claim 1, wherein the contact portion includes a cylindrical body that houses the elastic member and is open at one end . Comprising a plurality of said biasing means, these biasing means, the image forming apparatus according to claim 1, characterized in that it is arranged symmetrically with respect to the center in the extending direction of the rotation axis of the conveying roller . 3. The image forming apparatus according to claim 1, wherein the urging unit is disposed so as to avoid an area overlapping with a passing area of the recording medium in an extending direction of a rotation shaft of the transport roller. Said desorbing portion constitutes a part of a reverse path for reversing the recording medium, any one of claims 1-3, characterized in that opening the upper region of the fixing device when it was detached from the main body The image forming apparatus described in 1.