JP4375368B2 - Paper transport mechanism and image forming apparatus having the same - Google Patents

Description

  The present invention includes a drive shaft that is supported at both ends, a drive roller that is attached to the drive shaft and that transmits a driving force for transporting paper, and can be crimped to the outer peripheral surface of the drive roller. The present invention relates to a sheet conveying mechanism including a pressure roller for sandwiching a sheet to be printed and a biasing unit that biases the pressure roller toward the outer peripheral surface of a driving roller, and an image forming apparatus including the same.

  Such a paper transport mechanism is used as a plain paper transport mechanism in a facsimile machine or a multi-function machine (which corresponds to an image forming apparatus) having a copying function and a printing function. In such an image forming apparatus, a recording sheet (an example of a sheet) fed out from a recording sheet cassette is conveyed along a predetermined conveyance path and sent to a recording unit that forms an image on a recording surface of the recording sheet. In this transport path, the aforementioned paper transport mechanism is provided, and its configuration is shown in FIG.

  In FIG. 8, a plurality (three in the figure) of driving rollers 101 are attached to the driving shaft 100 along the axial direction. The drive shaft 100 is supported by bearings at both ends in the longitudinal direction by the frame member 102. The drive shaft 100 is connected to a drive motor (not shown). On the other hand, a pressure roller 103 is arranged to face each drive roller 101. The pressure roller 103 is attached to a roller shaft 104, and both longitudinal end portions thereof are supported by the frame portion 105. The roller shaft 104 is provided with two leaf springs 106 that function as urging means. The unit on the pressure roller 103 side is attached to an access cover 107 that can be opened and closed.

  The access cover 107 is rotatable around a fulcrum 107a (see arrow). Normally, the access cover 107 is in a closed state. When a conveyance failure such as a jam occurs, the access cover 107 is opened and the recording paper is loaded. It is something to take out. When the access cover 107 is closed, the pressure roller 103 is urged against the outer peripheral surface of the drive roller 101 by the urging force of the leaf spring 106. Accordingly, the recording paper can be conveyed while being sandwiched between the driving roller 101 and the pressure roller 103. At both ends that support the roller shaft 104, a long hole 105a is formed in the frame portion 105. When the access cover 107 is closed, the roller shaft 104 is configured to be movable along the long hole 105a. Thereby, the urging force by the leaf spring 106 is reliably applied.

  In the paper transport mechanism as described above, it is necessary to increase the length of the drive shaft 100 in the longitudinal direction in order to support A3 size or B4 size recording paper. Then, there is a problem in that the driving shaft 100 is bent and deformed when a pressing force by the pressing roller 103 is applied. If such bending deformation occurs, it may cause a conveyance failure and noise generation. Therefore, it is necessary to eliminate the bending deformation as much as possible. As conventional techniques for solving such problems, techniques disclosed in Patent Documents 1 and 2 below are known.

  Japanese Patent Application Laid-Open No. 2004-228561 discloses a paper transport device in an automatic document transport unit of an image forming apparatus. This paper conveying apparatus is provided with a plate-like holding member that has its lower end in contact with the central axis and suppresses the deflection of the central axis. This holding member is provided on the inner surface of the cover body in the automatic document feeder. Moreover, the structure which suppresses the bending of a center axis | shaft by making the lower end part of a leaf | plate spring contact is also disclosed.

  Patent Document 2 discloses a transport device used in an ink jet recording apparatus. In this transport device, the center support portion of the transport drive roller is slidably supported by the intermediate support member. The position of the middle support member is adjustable, and the bottom side of the middle support member is configured to abut on and support the outer peripheral surface of the eccentric cam of the adjustment member.

JP 2000-318851 A JP 2006-82439 A

  In the above-described prior art, the following problems still remain, although it is a configuration that suppresses the bending deformation of the drive shaft to which the drive roller is attached. That is, in Patent Document 1, the holding member is attached to the inner side surface of the cover body, and when a large force acts on the holding member, the cover body that is not so strong in strength can be adversely affected. There is sex. In particular, in the case of an access cover that can be opened and closed, if this is closed vigorously, a large force greater than the biasing force of the leaf spring may act on the drive shaft, resulting in a large deformation of the drive shaft. There is a case where it is going to be made to do.

  The configuration disclosed in Patent Document 2 also has a similar problem, and is not provided with a strength that can sufficiently withstand a large force acting on the drive shaft.

  The present invention has been made in view of the above circumstances, and its problem is to suppress the bending deformation of the drive shaft that supports the drive roller in the roller mechanism that sandwiches and conveys the paper by the pressure force of the drive roller and the pressure roller. It is an object of the present invention to provide a paper transport mechanism that can sufficiently withstand strength even if a large force is applied to a drive shaft carelessly and an image forming apparatus using the same.

In order to solve the above problems, a paper transport mechanism according to the present invention includes:
A drive shaft supported at both ends;
A driving roller attached to the driving shaft and to which a driving force for conveying the paper is transmitted;
A pressure roller that can be crimped to the outer peripheral surface of the drive roller and clamps the paper to be conveyed;
An urging means for urging the pressure roller in the direction of the outer peripheral surface of the drive roller;
A drive shaft pressing member that suppresses bending and deformation of the drive shaft by the biasing force of the biasing means;
A metal plate-like member to which the drive shaft pressing member is attached,
The plate-like member is fixed so that the direction in which the urging force acts is parallel or substantially parallel to the direction of the plate surface of the plate-like member ,
The drive shaft pressing member has a pair of presser protrusions that press the drive shaft portion on both outer sides in the axial direction of the drive roller,
The presser protrusion is provided with a recess or protrusion, and the plate-like member is provided with a protrusion or recess that fits into the recess or protrusion, and the presser protrusion moves by the biasing force due to the fitting function. This is characterized in that this is suppressed .

The operation and effect of the paper transport mechanism having such a configuration will be described. The paper is conveyed in a form that is sandwiched between a driving roller and a pressure roller. The pressure applied by the pressure roller is applied by the biasing means, and the pressure roller is biased in the direction of the outer peripheral surface of the drive roller. In addition, a drive shaft pressing member that suppresses bending and deformation of the drive shaft to which the drive roller is attached is provided. The drive shaft pressing member is attached to a metal plate-like member. When the urging force acts on the drive shaft, the plate-like member supports the drive shaft and suppresses bending deformation of the drive shaft. The direction in which the urging force acts is parallel or substantially parallel to the direction of the plate surface of the plate-like member. Therefore, since the urging force acts in a direction in which the metal plate-like member is hardly deformed, it is possible to reliably suppress the drive shaft pressing member from moving to the urging force. As a result, even if an inadvertently large force acts on the drive shaft, it can sufficiently withstand the strength. Further, by providing the fitting function as described above, when the presser protrusion receives an urging force, the urging force can be received by the fitting portion. Thereby, it is possible to suppress the presser protrusion from moving due to the urging force, and it is possible to more reliably suppress the bending deformation of the drive shaft.

In the present invention, a plurality of drive rollers are attached along the axial direction of the drive shaft, and the pair of pressing protrusions are formed on the drive shaft portions on both outer sides in the axial direction of the drive roller located at the center portion of the drive shaft. it is preferred holding Ru.

  By suppressing the positions on both sides of the drive roller located at the center of the drive shaft, it is possible to efficiently suppress the bending deformation of the drive shaft.

  In the present invention, the drive shaft pressing member is preferably formed of a resin material having self-lubricating properties.

  As a result, even if the drive shaft pressing member comes into contact with the drive shaft, it has a self-lubricating property, so that it is not necessary to apply a large load to the rotation of the drive shaft.

  An image forming apparatus employing a paper transport mechanism according to the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing an external configuration of the image forming apparatus 1. FIG. 2 is a schematic diagram showing in block form the internal configuration of the image forming apparatus shown in FIG. 2 is a schematic diagram viewed from the front side of the image forming apparatus. The direction perpendicular to the paper surface of FIG. 2 is the front-rear direction of the apparatus, the vertical direction along the paper surface of FIG. The horizontal direction along the plane of the paper is defined as the horizontal direction of the device.

  The image forming apparatus 1 can be roughly divided into an upper main body 1A and a lower main body 1B. The upper main body 1A includes an automatic document feeder (hereinafter referred to as ADF) 2 at the top, and includes a document tray 2a, a feed conveyance mechanism 2b, and a discharge tray 2c. The documents stacked and placed on the document tray 2a are separated one by one by the feeding and conveying mechanism 2b, and an image is read by the stationary reading and scanning device 3a at the reading point P in the middle of the conveying path. The document whose image has been read is sequentially discharged to the discharge tray 2c.

  The image reading unit 3 includes an ADF reading unit 3b and a flat head scanner unit (FBS) 3c. When the image reading is performed in the FBS 3c, the reading scanning device 3a moves to the FBS 3c, and reads an image of a document placed under the platen glass 3d while reciprocating in the left-right direction under the platen glass 3d. A series of mechanisms constituting the ADF 2 also serves as a platen cover (document pressing plate), and can be opened and closed with the back side of the sheet of FIG. 1 as a hinge shaft.

  The image recording unit 4 is an electrophotographic recording device, and includes a photoconductor drum (not shown), a charger, a laser light writing unit, a developing device, a transfer device, a fixing device, and the like. The recording paper on which the image is formed is discharged to the discharge tray 4b by the discharge roller 4a. As a specific configuration of the image recording unit 4, a known configuration can be adopted. As the electrophotographic format, various image recording methods such as an ink jet method and an ink ribbon method can be employed in addition to a method of transferring a toner image onto a recording paper. The formed image may be either a monochrome image or a color image.

  The paper supply unit 5 includes three recording paper cassettes 6 that can be taken in and out in a direction perpendicular to the paper surface of FIG. Each recording paper cassette 6 basically has the same structure. In the recording paper cassette 6, recording paper is stacked and stored in the vertical direction, and is separated and fed out one by one by the paper feed roller 6a. A well-known configuration can be adopted for the paper feed mechanism by the paper feed roller 6a. The recording paper fed out by the paper supply roller 6 a is sent to the image recording unit 4 by the paper transport mechanism C.

  The paper transport mechanism C includes a driving roller 10 and a pressure roller 11, and the same roller mechanism is adopted for each recording paper cassette 6. In the paper transport mechanism C, the driving roller 10 is attached to the main body frame side, and the pressure roller 11 is attached to the access cover 12 side that can be opened and closed. The access cover 12 is provided on the right side surface portion of the image forming apparatus 1, and the same number as the number of the recording paper cassettes 6 is provided. The access cover 12 is provided for performing maintenance such as opening a recording paper when a trouble such as a jam occurs when the recording paper is conveyed. The access cover 12 is attached in a vertical posture, and a hinge shaft 12a is provided at the lower part thereof. As shown in FIG. 1, the access cover 12 is provided with an operation unit 12 b, and the access cover 12 can be manually opened by inserting a finger therein.

  As shown in FIG. 1, an operation panel 7 is provided on the front surface of the upper main body 1A. The operation panel 7 is provided with key buttons for performing various operations, a liquid crystal display unit, and the like.

<Paper transport mechanism>
Next, the configuration of the paper transport mechanism C shown in FIG. 2 will be described. 3 and 4 both show a state in which the upper body 1A is removed and the uppermost part of the lower body 1B is exposed. 3 shows a state in which the access cover 12 is closed, and FIG. 4 shows a state in which the access cover 12 located at the top in FIG. 2 is opened. FIG. 5 is a plan view showing the configuration of the paper transport mechanism C with the access cover 12 closed, and FIG. 6 is a partially exploded perspective view showing the configuration of the paper transport mechanism C.

  A driving roller 20 and a pressure roller 30 are provided to sandwich and convey the recording paper. The drive roller 20 is attached to a drive shaft 21 extending along the front-rear direction of the apparatus, and the three drive rollers 20 are arranged at equal intervals. Three pressure rollers 30 are arranged corresponding to the three drive rollers 20. However, in the present invention, it is possible to appropriately determine how many drive rollers 20 and pressure rollers 30 are arranged. As an example, the drive roller 20 can be a rubber roller, and the pressure roller 30 can be a synthetic resin roller.

  Both ends in the longitudinal direction of the drive shaft 21 are pivotally supported by bearings (not shown) attached to the support frame 22. One end of the drive shaft 21 in the longitudinal direction is connected to the drive mechanism 23. The drive mechanism 23 includes a drive motor and a speed reduction mechanism connected to the drive motor.

  As shown in FIG. 4, the unit including the pressure roller 30 is attached to the access cover 12. The pressure roller 30 is attached to a roller shaft 31, and both ends thereof are pivotally supported by a support frame 33 formed integrally with the access cover 12. A long hole 33a for shaft support is formed in the support frame 33. A leaf spring 32 (corresponding to the biasing means) acts on the roller shaft 31 and presses the outer peripheral surface of the pressure roller 30 against the outer peripheral surface of the driving roller 20 when the access cover 12 is closed. As a result, the recording paper can be nipped and conveyed by a desired pressing force.

  The leaf spring 32 is attached so as to act on the portion of the roller shaft 31 positioned between the pressure roller 30 and the pressure roller 30, and the tip portion of the leaf spring 32 is inserted into the space between the roller shaft 31 and the access cover 12. It is. The root portion of the leaf spring 32 is fixed to the access cover 12 with a screw 34. Although two leaf springs 32 are attached in total, the number of arrangements can be changed as appropriate. Note that the urging means for applying the crimping force may not be the leaf spring 32 but may be constituted by a coil spring, for example.

  As shown in FIG. 4, when the access cover 12 is opened, the pressure roller 30 unit is urged in the direction of protruding entirely by the urging force of the leaf spring 32. Accordingly, the roller shaft 31 comes into contact with the end surface portion of the elongated hole 33a.

  When the access cover 12 is closed, the pressure applied by the pressure roller 30 acts on the drive roller 20, so that a force that bends and deforms the drive shaft 21 acts. Therefore, a drive shaft pressing member 24 is provided to suppress the bending deformation of the drive shaft 21, and the drive shaft pressing member 24 is further fixed to a metal plate-like member 25. The plate-like member 25 has a plate shape as a whole, and is formed of a metal such as stainless steel. The plate-like member 25 is fixed to the lower main body 1B with screws.

  As shown in FIG. 6, in order to attach the drive shaft pressing member 24, a cutout portion 25a is formed at the center in the front-rear direction on the right side. The cutout portion 25a is configured as a flat portion that is one step lower than the surroundings. The cutout portion 25a is formed with a female screw 25b at the center, and two positioning holes 25c are formed on both sides in the front-rear direction.

  The shape of the upper surface side of the drive shaft pressing member 24 is shown in FIG. 6A, and the shape of the lower surface side is shown in FIG. 6B. The drive shaft pressing member 24 is integrally formed with a pair of presser protrusions 24 a for pressing the deformation of the drive shaft 21. As shown also in FIG. 5, it acts so that the bending deformation of the drive-shaft 21 part may be suppressed in the axial direction both sides of the drive roller 30 located in the center. A fitting groove 24b (corresponding to a concave portion) is formed in the lower part of the presser protrusion 24a, and is fitted to a vertical wall surface portion 25d (corresponding to a convex portion) of the plate-like member 25. With this fitting function, the pressing force of the pressing roller 30 can be reliably received by the presser protrusion 24a, and the bending deformation of the drive shaft 21 can be reliably suppressed. In addition, you may form a convex part in the presser protrusion part 24a, and form a recessed part in the plate-shaped member 25, and may exhibit a fitting function.

  The drive shaft pressing member 24 can be molded from a synthetic resin, and is preferably molded from a resin having self-lubricating properties such as POM (polyacetal). Thereby, even if the drive shaft 21 is rotationally driven in a state where the presser protrusion portion 24a is in contact with the drive shaft 21, the load can be reduced.

  A stepped screw hole 24 c for connecting the drive shaft pressing member 24 to the female screw 25 b of the plate-like member 25 with a screw 26 is provided. Further, as shown in FIG. 6B, positioning protrusions 24 d are formed on the back surface and are inserted into the positioning holes 25 c of the plate-like member 25.

  FIG. 7 is a diagram illustrating a positional relationship between the driving roller 20 and the pressure roller 30 in a state where the access cover 12 is closed. In this state, the unit of the pressure roller 30 moves slightly to the right against the urging force of the leaf spring 32. At this time, since the roller shaft 31 is pivotally supported by the elongated hole 33a, the unit moves smoothly. Thereby, desired crimping | compression-bonding force can be made to act.

  Further, the direction of the crimping force acting at this time is from the right side to the left side as indicated by an arrow in FIG. This direction is a direction parallel to or substantially parallel to the plate surface of the plate-like member 25, and acts in a direction in which the plate-like member 25 is extremely difficult to deform. This is because the plate-like member 25 is pressed from the end surface side. Therefore, even if a large pressure bonding force is applied, there is no problem with strength and it can be reliably received. In particular, when the access cover 12 is closed, the access cover 12 may be closed with great force. At this time, a large force is instantaneously applied to the drive shaft 21. It can be received by the member 24.

  Further, the drive shaft pressing member 24 itself has a body portion 24e formed in a plate shape, and a pressing force acts in the direction of the plate surface. Also in this respect, the pressure-bonding force can be reliably received, and the bending deformation of the drive shaft 21 can be effectively suppressed.

<Another embodiment>
The image forming apparatus 1 of the present embodiment has a structure having a flat bed type structure, but the document reading method may have a structure having only a sheet feed type that is read by the ADF 2. The image forming apparatus 1 may have a facsimile function.

The perspective view which shows the external appearance structure of an image forming apparatus Schematic diagram showing in block form the internal configuration of the image forming apparatus A perspective view showing the configuration of the paper transport mechanism with the access cover closed A perspective view showing the configuration of the paper transport mechanism with the access cover open Top view showing the configuration of the paper transport mechanism with the access cover closed Partially exploded perspective view showing the configuration of the paper transport mechanism Sectional view showing the configuration with the access cover closed The figure which shows the structure of the paper conveyance mechanism which concerns on a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 1A Upper main body 1B Lower main body 20 Drive roller 21 Drive shaft 24 Drive shaft pressing member 24a Press protrusion 24b Fitting groove 25 Plate-shaped member 30 Pressure roller 31 Roller shaft 32 Plate spring 33 Support frame C Paper conveyance mechanism

Claims (4)

A drive shaft supported at both ends;
A driving roller attached to the driving shaft and to which a driving force for conveying the paper is transmitted;
A pressure roller that can be crimped to the outer peripheral surface of the drive roller and clamps the paper to be conveyed;
An urging means for urging the pressure roller in the direction of the outer peripheral surface of the drive roller;
A drive shaft pressing member that suppresses bending and deformation of the drive shaft by the biasing force of the biasing means;
A metal plate-like member to which the drive shaft pressing member is attached,
The plate-like member is fixed so that the direction in which the urging force acts is parallel or substantially parallel to the direction of the plate surface of the plate-like member ,
The drive shaft pressing member has a pair of presser protrusions that press the drive shaft portion on both outer sides in the axial direction of the drive roller,
The presser protrusion has a recess or protrusion, and the plate-like member has a protrusion or recess that fits into the recess or protrusion, and the presser protrusion moves by the biasing force due to the fitting function. A paper transport mechanism characterized by suppressing this . Along the axial direction of the drive shaft is mounted a plurality of drive rollers, the pair of pressing projections, that Ru pressing the drive shaft portion in the axial end outside drive roller positioned at the center of the drive shaft The paper transport mechanism according to claim 1, wherein The drive shaft holding member, the paper conveying mechanism according to claim 1 or 2, characterized in that it is formed of a resin material having self-lubricating property. An image forming apparatus having a sheet conveying mechanism according to any one of claims 1-3.

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