JP5893996B2 - Paper transport device - Google Patents

Description

  In the present invention, in order to remove jammed paper generated between the upper and lower paper transport guide plates that guide the paper transport, the lower paper transport guide plate is directed downward from the paper transport operation position along the paper transport path. Sheet conveying apparatus configured to avoid the influence of the weight of the lower sheet conveying guide plate and the weight of the sheet conveying member attached to the lower sheet conveying guide plate when rotating to a retracted position spaced apart About.

  In general, printing apparatuses that print images and characters on paper and image forming apparatuses such as copying machines that copy images and characters on paper are widely used.

  This type of image forming apparatus includes a paper feeding unit that feeds paper, an image forming unit that forms an image on the paper, and a paper discharge unit that discharges the paper on which the image has been formed.

  A paper feed side paper transport unit is provided for transporting paper along a paper feed side paper transport path set between the paper feed unit and the image forming unit, and between the image forming unit and the paper discharge unit. A paper discharge side paper transport unit is provided for transporting paper along the paper discharge side paper transport path set in the above.

  At this time, in general, at least one of the paper conveyance unit (paper conveyance device) on the paper supply side and the paper discharge side is a paper conveyance path in which upper and lower paper conveyance guide plates for guiding conveyance of the paper are set in the apparatus main body. The upper and lower paper transport guide plates are provided with paper transport members such as upper and lower paper transport rollers and a paper transport belt, which are rotatable to transport the paper. It has been.

  The sheet is conveyed by the upper and lower sheet conveying members in the order of the sheet feeding unit, the image forming unit, and the sheet discharging unit while being along the upper and lower sheet conveying guide plates. For some reason, the upper and lower sheet conveying guide plates In some cases, paper jams and paper jam occurs.

  On the other hand, in order to remove jammed paper generated during the transport of the paper, the frame supporting the lower transport guide plate among the upper and lower transport guide plates is directed downward from the paper transport operation position along the paper transport path. There is an image recording apparatus that is provided so as to be rotatable to a retracted position separated from each other (see, for example, Patent Document 1).

  In the image recording apparatus disclosed in Patent Document 1, a photosensitive drum is rotatably provided in the apparatus main body, although illustration is omitted here.

  Further, between the paper feed tray and the paper discharge tray, a mechanism that constitutes a transport system for transporting the transfer paper (paper) is divided into upper and lower components of the transfer paper transport path. Yes.

  A gantry is provided on the lower side of the transfer paper so as to be rotatable in the vertical direction. Each member constituting the lower part of the gantry, that is, the lower conveyance guide plate, A registration roller and a lower conveyor belt are attached.

  When an image is formed on transfer paper in this image recording device, the free end of the leaf spring is pushed up with a roller at the swinging tip of the release arm attached to the base, and the lower base is brought into the transfer path of the transfer paper. Rotate upward along the line to stop at the specified position (paper conveyance operating position), and move the lower conveyance guide plate, lower registration roller, lower conveyance belt, etc. along the lower side of the transfer paper. The transfer paper is conveyed between the upper and lower conveyance guide plates.

  On the other hand, if the transfer paper stays in the transfer paper transport path and a jam occurs, the user manually operates the release arm to move the frame against the biasing force of the leaf spring. It is described that the sheet is rotated downward so as to be separated from the sheet and stopped at the retracted position, and the transfer sheet on which the jam has occurred is removed.

JP-A-60-123877

  By the way, in the image recording apparatus disclosed in Patent Document 1, as described above, when a jam occurs in the transfer paper transport track, the transfer paper transport track resists the urging force of the leaf spring. The transfer paper in which the jam has occurred can be easily removed by rotating downward so as to be separated from the transfer paper and resting at the retracted position.

  However, because the lower carrier guide plate, lower registration roller, lower carrier belt, etc. are attached to the heavy platform, when removing the jammed transfer paper, the platform is moved downward. When rotating to the retracted position, the weight of the gantry, the lower conveyance guide plate, the lower registration roller, the lower conveyance belt, etc. causes the gantry to open downward and force the user It will be burdensome.

  On the other hand, when an image is formed on the transfer paper, when the gantry is rotated to the sheet conveyance operation position set below the upper conveyance guide plate, the gantry, the lower conveyance guide plate, the lower registration roller, Each weight of the lower conveyor belt has an adverse effect that the operating force to the gantry increases.

  Each of the above-described adverse effects is caused by the weight of the gantry side and the action of the leaf spring that urges the gantry.

  At this time, the action of the leaf spring is such that, when the gantry is positioned at the upper paper transport operation position, the assisting force that urges the gantry in the direction facing the gantry is small, and the spring of the leaf spring On the other hand, when the gantry is located at the retracted position below, the auxiliary force is large and the spring force of the leaf spring is small, so the influence of the weight on the gantry side cannot be avoided. .

  Therefore, upper and lower paper transport guide plates that guide the transport of paper are provided separately on the upper and lower sides of the paper transport path set in the main body, and the paper transport members are attached to the upper and lower paper transport guide plates, respectively. In addition, in order to remove the jammed paper generated between the upper and lower paper transport guide plates, the lower paper transport guide plate is moved from the paper transport operation position along the paper transport path to the retracted position spaced downward. An object of the present invention is to provide a sheet conveying apparatus configured to avoid the influence of the weight of a lower sheet conveying guide plate and the weight of a sheet conveying member attached to the lower sheet conveying guide plate when rotating. And

The present invention has been made in view of the above problems, and the invention according to claim 1 is an upper side and a lower side of a sheet conveying path in which upper and lower sheet conveying guide plates for guiding sheet conveyance are set in the apparatus main body. In order to remove jammed paper generated between the upper and lower paper transport guide plates after the paper transport members are respectively attached to the upper and lower paper transport guide plates, the lower paper transport In the sheet conveying apparatus configured to rotate the guide plate from the sheet conveying operation position along the sheet conveying path to the retracted position spaced downward about the rotation axis provided in the apparatus main body,
A first link member whose one end is pivotally supported by a link support disposed below the rotation shaft of the lower paper transport guide plate in the apparatus body;
A second link member having one end overlapped with the other end of the first link member and pivotally supported, and the other end opposite to the one end is pivotally supported by the lower sheet transport guide plate; ,
One end side is hooked to the spring support portion disposed below the link support portion in the apparatus body, and the other end side opposite to the one end side is hooked to the intersection of the first and second link members, A tension spring that urges the weight of the lower paper transport guide plate and the weight of the paper transport member attached to the lower paper transport guide plate to cancel each other;
There is provided a sheet conveying device characterized by comprising:

  According to the paper transport apparatus of claim 1, the upper and lower paper transport guide plates for guiding the transport of the paper are provided separately on the upper and lower sides of the paper transport path set in the apparatus main body, and A paper transport guide plate on the lower side that regulates the paper transport path to remove jammed paper generated between the upper and lower paper transport guide plates after attaching the paper transport members to the paper transport guide plate, and the apparatus main body By incorporating a four-bar linkage mechanism and a tension spring between the link support and spring support provided inside, the lower paper transport guide plate closes and the paper transport along the paper transport path When in the operating position, the assisting force is opposite to the opening direction due to the total gravity, which is the sum of the weight of the lower paper transport guide plate and the gravity of the paper transport member attached to the lower paper transport guide plate. For lower power On the other hand, when the lower paper transport guide plate is open and located at the retracted position spaced downward from the paper transport operation position, auxiliary power is applied to the lower paper transport guide plate. As a result, when the user manually opens the lower paper transport guide plate, the lower paper transport guide plate does not open vigorously downward, reducing the burden on the user. In addition, when the user manually closes the lower paper transport guide plate, the operating force on the lower paper transport guide plate can be reduced.

1 is an overall configuration diagram illustrating an overall configuration of an image forming apparatus to which a sheet conveying device according to the present invention is applied. (A), (b) is an operation diagram for explaining a state in which the second lower sheet conveyance guide plate rotatably provided in the sheet conveyance apparatus according to the present invention is located at the sheet conveyance operation position. It is. (A), (b) is an operation | movement diagram for demonstrating the state which the 2nd lower side paper conveyance guide plate provided in the paper conveyance apparatus which concerns on this invention rotatably was located in a retracted position. .

  In the following, a preferred embodiment of the paper conveying apparatus according to the present invention will be described in detail with reference to FIGS.

  FIG. 1 shows the overall configuration of an image forming apparatus to which a paper conveying apparatus according to the present invention is applied.

  As shown in FIG. 1, an image forming apparatus 1 to which a paper transport device 30 according to the present invention is applied is used in a printing apparatus that prints images and characters on paper P, a copying machine that copies images and characters on paper P, and the like. It has been.

  In the image forming apparatus 1 described above, in order from the upstream side to the downstream side in the paper conveyance direction, the paper feeding unit 10 that feeds the paper P, the roller driving unit 20, and the fed paper P toward the downstream. A paper feed side paper transport unit (paper transport device) 30 that transports, an image forming unit 50 that forms an image on the paper P, and a paper discharge side paper transport unit 60 that transports the image-formed paper P downstream. And a paper discharge unit 70 that discharges the image-formed paper P, and a control unit 80 that controls the image forming apparatus 1 as a whole.

  The paper transport device 30 according to the present invention is configured as a paper feed-side paper transport unit in this embodiment, but the paper transport device 30 can also be applied to the paper discharge-side paper transport unit. The present invention can be applied to any paper transport unit that transports the paper P.

  Here, each component of the image forming apparatus 1 will be described in order.

  First, in the paper feeding unit 10, a paper feeding base 11 on which a plurality of papers P are stacked is installed so as to be movable up and down by a motor with an encoder (not shown), a pinion gear, and a rack.

  In addition, a paper feed roller 12 is provided above the paper feed tray 11 so as to be able to rotate counterclockwise. The paper feed roller 12 contacts the uppermost sheet P as the paper feed stand 11 moves upward. In contact therewith, the uppermost sheet P is fed.

  Further, the uppermost sheet P fed by the sheet feeding roller 12 is conveyed one by one while being nipped and conveyed between the separating roller 13 and the friction plate 14 provided downstream of the sheet feeding roller 12 in the sheet conveying direction. Separated to prevent double feeding, the uppermost sheet P is then conveyed downstream.

  At this time, the rotation of the first motor 21 provided in the roller driving unit 20 is decelerated to a constant conveyance speed by the gear train 22 and is transmitted to the paper feeding roller 12 and the roller 13, so that Each of the rollers 13 is driven to rotate counterclockwise so that the paper P is conveyed at a predetermined conveyance speed.

  Next, the sheet conveying device (sheet feeding side sheet conveying unit) 30 is installed along a sheet feeding side sheet conveying path KR set in the apparatus main body (not shown) between the sheet feeding unit 10 and the image forming unit 50. Has been.

  In the paper transport device (paper feed side paper transport unit) 30, an upper paper transport guide plate 31 that guides the upper surface side of the paper P is fixedly installed above the paper feed side paper transport path KR.

  A first lower sheet conveyance guide plate 32 for guiding the lower surface side of the sheet P is fixedly installed on the upstream side below the sheet conveyance path KR.

  Further, a second lower sheet conveyance guide plate 33 that guides the lower surface side of the sheet P downstream from the first lower sheet conveyance guide plate 32 below the sheet feeding side sheet conveyance path KR is provided. A first pivot shaft 34 attached between a pair of side plates (not shown) of the main body is provided so as to be pivotable in the vertical direction.

  Accordingly, the upper sheet conveyance guide plate 31 and the first and second lower sheet conveyance guide plates 32 and 33 are provided separately on the upper and lower sides with the sheet feeding side sheet conveyance path KR interposed therebetween.

  When the paper transport device (paper feed side paper transport unit) 30 in the image forming apparatus 1 is in the initial state (standby state) and the normal printing state, the upper paper transport guide plate 31 and the first and second The lower paper conveyance guide plates 32 and 33 are opposed to each other with a slight gap set by a stopper member (not shown).

  At this time, the rotatable second lower paper conveyance guide plate 33 is rotated downward when a paper jam occurs in the paper supply side paper conveyance path KR, whereby a jammed paper JP, which will be described later, is provided. (FIG. 3) is provided so that the user can easily remove it.

  Accordingly, the second lower paper transport guide plate 33 is positioned at the paper transport operation position set along the paper transport path KR when transporting the paper P, and on the other hand when the paper jam occurs. It can be manually moved up and down so as to be located at a retracted position spaced downward from the path KR.

  Further, the upper sheet conveying guide plate 31 is bent using a sheet metal material, and a first horizontal surface 31a is formed at a height higher than the winding roller 13, and is connected to the first horizontal surface 31a. The inclined surface 31b is formed to be inclined at a predetermined angle downward, and the second horizontal surface 31c is formed at a low height so as to be connected to the inclined surface 31b, and is elongated along the sheet conveying direction. Is formed.

  The upper sheet conveyance guide plate 31 has a pair of side surfaces 31d and 31e bent upward at both ends in the width direction orthogonal to the conveyance direction of the sheet P.

  On the other hand, the first lower paper conveyance guide plate 32 is also bent using a sheet metal material, and the horizontal surface 32a is slightly spaced from the first horizontal surface 31a of the upper paper conveyance guide plate 31 downstream of the winding roller 13. A pair of side surfaces 32b and 32c are formed to be bent downward at both ends in the width direction perpendicular to the transport direction of the paper P. Yes.

  The second lower paper transport guide plate 33 is also bent using a sheet metal material, and the inclined surface 33a is located on the lower side of the horizontal surface 32a of the first lower paper transport guide plate 32 and the upper paper transport guide. Opposite the inclined surface 31b of the plate 31 with a slight gap, it is elongated along the paper transport direction, and a pair of side surfaces 33b on both ends in the width direction perpendicular to the paper P transport direction. , 33c are bent downward.

  Further, between the pair of side surfaces 31d and 31e of the upper sheet conveyance guide plate 31, first, second, and third sheet conveyance drive rollers 35A, 36A, and 37A serving as sheet conveyance members are spaced apart from each other by a predetermined interval. It is attached.

  The first, second, and third paper transport driving rollers 35A, 36A, and 37A are decelerated to a constant transport speed via the first motor 21 and the gear train 22 provided in the roller driving unit 20. Each of them is driven to rotate counterclockwise.

  On the other hand, between the pair of side surfaces 32b and 32c of the first lower sheet conveyance guide plate 32, a first sheet conveyance driven roller 35B is attached to make a pair with the first sheet conveyance drive roller 35A. At the same time, between the pair of side surfaces 33b and 33c of the second lower paper transport guide plate 33, the second and third paper transport driven rollers 36B and 37B are also connected to the second and third paper transport drive rollers 36A and 37A. It is attached to make a pair.

  At this time, the first horizontal surface 31 a and the inclined surface 31 b of the upper paper conveyance guide plate 31, the horizontal surface 32 a of the first lower paper conveyance guide plate 32, and the inclined surface 33 a of the second lower paper conveyance guide plate 33. The first, second, and third paper transport driving rollers 35A, 36A, and 37A and the first, second, and third paper transport driven rollers 35B, 36B, and 37B can contact each other in pairs. In addition, escape holes that face each roller are formed.

  From the above, the first, second, and third paper transport driving rollers 35A, 36A, and 37A are attached to the fixed upper paper transport guide plate 31, and the first, second, and third paper transport driven rollers are attached. By attaching the 35B, 36B, and 37B to the first and second lower paper transport guide plates 32 and 33 that are rotatable, the paper transport device (paper feed paper transport section) 30 can be simply configured.

  Further, a light reflection type paper feed sensor 38 for detecting whether or not the paper P is fed from the paper feed unit 10 is installed downstream of the first paper transport driving roller 35A.

  Here, when the second lower paper conveyance guide plate 33 is pivotally supported by the first rotation shaft 34, the weight of the second lower paper conveyance guide plate 33 and the second In order to reduce the influence of the weights of the second and third paper transport driven rollers 36B and 37B as the paper transport members attached to the lower paper transport guide plate 33, in this embodiment, the following link mechanism is used as a countermeasure. I am trying.

  That is, the link support portion 40 is fixedly disposed at a position below the first rotation shaft 34 of the second lower paper transport guide plate 33 in the apparatus main body. One end portion side of the first link member 42 is pivotally supported by the provided second rotating shaft 41.

  A third rotating shaft 43 is attached to the other end side opposite to the one end side of the first link member 42, and the second link member 44 is attached to the third rotating shaft 43. The other end side of the first link member 42 and the one end side of the second link member 44 are overlapped with each other with the third rotation shaft 43 as an intersection. The second link members 42 and 44 are pivotally supported so as to be rotatable.

  Further, the second lower paper transport guide plate 33 is transported between the pair of side surfaces 33b and 33c at positions farther from the first rotating shaft 34 in the longitudinal direction. A fourth rotation shaft 45 is attached to a substantially intermediate position between the driven rollers 36B and 37B, and the other end side of the second link member 44 is pivotally supported by the fourth rotation shaft 45.

  Further, an operation lever 46 having a lock claw 46a is fixed to one end portion of the fourth rotation shaft 45 on the near side of the figure, and the second lower shaft is manually operated by the user. The side paper conveyance guide plate 33 can be opened and closed.

  At this time, when the second lower sheet conveyance guide plate 33 is located at the sheet conveyance operation position, the lock claw 46a of the operation lever 46 is at a position where the conveyance of the sheet P is not hindered and the upper and lower sheets The sheet is locked to the upper sheet conveyance guide plate 31 in a state where a predetermined interval is maintained between the conveyance guide plates 31 and 33.

  Therefore, the link mechanism includes a first virtual link member (not shown) that virtually connects the first rotation shaft 34 and the second rotation shaft 41, and the second rotation shaft 41 and the third rotation shaft 41. The first link member 42 that connects the rotation shaft 43, the second link member 44 that connects the third rotation shaft 43 and the fourth rotation shaft 45, the fourth rotation shaft 45, and the second The four link members 34, 41 to 45 are configured by four link members including a second virtual link member (lower sheet conveyance guide plate 33) that virtually connects one rotation shaft 34. .

  At this time, the length of each arm of the four link members is preset at the time of design so that the four-bar linkage mechanism 34, 41 to 45 is established, as will be described later.

  The first and second rotating shafts 34 and 41 are fixed shafts fixed in the apparatus main body, while the third and fourth rotating shafts 43 and 45 are the second lower sheet. This is a displacement axis whose position is displaced as the conveyance guide plate 33 rotates.

  Further, a spring support portion 47 is fixedly disposed at a position below the link support portion 40 described above, and one end side of the tension spring 49 is hooked on a spring latch pin 48 provided on the spring support portion 47. ing. Further, the other end side of the tension spring 49 is hooked to a third rotating shaft 43 which is an intersection where the first and second link members 42 and 44 overlap each other.

  The tension spring 49 is formed by the weight of the second lower paper transport guide plate 33 and the second and third paper transport driven rollers 36B serving as the paper transport members attached to the second lower paper transport guide plate 33. , 37B is provided with a function of biasing in a direction to cancel the weight.

  Accordingly, in the sheet conveying device (sheet feeding side sheet conveying section) 30 having the above-described configuration, the second lower sheet conveying guide plate 33 is rotated using the four-bar linkage mechanism 34, 41 to 45 and the tension spring 49. By supporting it freely, as will be described later, an auxiliary force F (FIG. 2, FIG. 2) that urges the gantry against the gravity on the second lower paper transport guide plate 33 side via a tension spring 49. 3) can be changed according to the rotational position of the second lower paper conveyance guide plate 33, so that the operating force to the second lower paper conveyance guide plate 33 can be adjusted. The operation of the paper transport device (paper feed side paper transport unit) 30 will be described in detail later.

  Next, the image forming unit 50 installed on the downstream side of the paper feeding side paper transport unit 30 uses an ink jet printing method, a stencil printing method, a thermal transfer printing method, a laser beam printing method, etc. Is printed or copied.

  In the image forming unit 50, a paper transport guide plate 51 for guiding the transport of the paper P is installed as necessary so as to be compatible with the printing method.

  Next, the paper discharge side paper conveyance unit 60 is installed along the paper discharge side paper conveyance path HR set downstream of the image forming unit 50. In the paper discharge side paper transport unit 60, an endless belt 64 is stretched between a driving pulley 62 that is rotated clockwise by a second motor 61 and a driven pulley 63, and the paper P on which an image has been formed is rotated. The paper P is mounted on a free endless belt 64 and is conveyed toward the paper discharge unit 70 described below while the air suction unit 65 sucks the paper P by air.

  In this embodiment, the paper P on which the image has been formed is transported by air suction onto the endless belt 64 by the paper discharge side paper transport unit 60. However, if the image forming surface of the paper P is dry. The paper discharge side paper conveyance unit may be configured similarly to the paper supply side paper conveyance unit described above.

  At this time, a light reflection type paper discharge sensor 66 for detecting a paper discharge state of the image-formed paper P is installed along the paper discharge side paper transport path HR.

  Next, the paper discharge unit 70 stacks the image-formed paper P sent from the paper discharge side paper transport unit 60 on the paper discharge table 71.

  Next, the control unit 80 is installed at an appropriate position in the apparatus main body. The control unit 80 controls the above-described components as a whole, and passes the paper P between the paper feed sensor 38 and the paper discharge sensor 66 when an image is formed on the paper P as will be described later. A paper jam detection unit that has a function of measuring time and determining whether or not to continue the conveyance of the paper P as it is, and further detects a paper jam that occurs in the paper conveyance device (paper conveyance side paper conveyance unit) 30 It also has the function.

  Here, the operation of the sheet conveying apparatus (paper feeding side sheet conveying unit) 30 according to the present invention will be described with reference to FIG. 1 and the new FIGS.

  2A and 2B show a state in which the second lower paper transport guide plate 33 provided rotatably in the paper transport device 30 according to the present invention is located at the paper transport operation position. It is an operation | movement diagram for demonstrating.

  As shown in FIG. 2A, the four-bar linkage mechanisms 34 and 41 to 45 that rotatably support the second lower paper transport guide plate 33 in the paper transport device 30 have been described with reference to FIG. It is constituted similarly.

  When the sheet conveying device 30 in the image forming apparatus 1 is in an initial state (standby state) or a normal printing state, the second lower sheet conveying guide plate 33 is centered on the first rotation shaft 34. Since it rotates counterclockwise and is positioned at the paper transport operation position along the paper feed side paper transport path KR, the upper paper transport guide plate 31 and the first and second lower paper transport guide plates 32. , 33 are opposed to each other with a slight gap across the paper feed side paper transport path KR.

  Accordingly, the paper P fed by the paper feeding unit 10 is guided between the upper paper transport guide plate 31 and the first and second lower paper transport guide plates 32, 33 while being guided by the first, second, and second paper transport guide plates 32, 33. It is nipped and driven by the third paper transport driving rollers 35A, 36A, and 37A and the first, second, and third paper transport driven rollers 35B, 36B, and 37B and transported to the image forming unit 50.

  Then, the control unit 80 measures the passage time of the paper P between the paper feed sensor 38 and the paper discharge sensor 66 during image formation on the paper P, and if this passage time is within a preset time. The conveyance to the paper P is continued as it is.

  At this time, the gravity (weight) of the second lower paper transport guide plate 33 and the gravity (weight) of the second and third paper transport driven rollers 36B and 37B attached to the second lower paper transport guide plate 33. ) Is added to the fourth rotation shaft 45 that pivotally supports the second lower paper conveyance guide plate 33 and the second link member 44, and this total gravity G Is a component force Gx obtained by disassembling the second lower paper conveyance guide plate 33 in the vertical direction, in other words, a component force Gx in the rotational direction of the second lower paper conveyance guide plate 33 is obtained. The reaction force due to Gx becomes the auxiliary force F to the second lower paper conveyance guide plate 33, and the auxiliary force F applied to the fourth rotating shaft 45 attached to the second lower paper conveyance guide plate 33 is the first. Large value.

  On the other hand, the spring force B of the tension spring 49 is applied to the third rotating shaft 43 that pivotally supports the first link member 42 and the second link member 44, and this spring force B is small.

  Accordingly, when the second lower paper transport guide plate 33 is closed and positioned at the paper transport operation position, the gravity of the second lower paper transport guide plate 33 and the second lower paper transport guide The total gravity G obtained by adding the gravity of the second and third paper transport driven rollers 36B and 37B attached to the plate 33 is canceled by a large auxiliary force F equivalent to the reaction force of the gravity G due to the component force Gx. Can do.

  FIG. 2B shows a simplified illustration of the four-bar linkage mechanism 34, 41 to 45 in a state where the second lower paper transport guide plate 33 is closed and positioned at the paper transport operation position. .

  In FIG. 2B, the first rotation shaft 34 is “b”, the second rotation shaft 41 is “b”, the third rotation shaft 43 is “c”, the fourth If the rotation axis 45 is “d”, there is a “c” on the inside of the triangle “iron” that connects “b”, “b” and “d”. Mechanisms 34 and 41 to 45 are established.

  Next, FIGS. 3A and 3B illustrate a state in which the second lower paper transport guide plate 33 provided rotatably in the paper transport device 30 according to the present invention is located at the retracted position. FIG.

  As shown in FIG. 3A, during the image formation on the paper P, the control unit 80 measures the passage time of the paper P between the paper feed sensor 38 and the paper discharge sensor 66, and this passage time is measured. When a preset time or more has elapsed, it is determined that a paper jam has occurred, and the conveyance of the paper P is stopped.

  Here, when a paper jam occurs, the user opens an openable / closable door (not shown) attached to the apparatus main body, and then moves the operation lever 46 attached to the second lower paper conveyance guide plate 33 side. The operation lever 46 is manually operated counterclockwise to unlock the operation lever 46 by the lock claw 46a.

  Then, by operating the operation lever 46, the second lower paper transport guide plate 33 is rotated clockwise about the first rotation shaft 34, so that the second lower paper transport guide plate 33 is From the paper transport operation position, the retreat position is spaced downward, and the user can easily remove the jammed paper JP at this retreat position.

  At this time, the sum of the weight of the second lower paper transport guide plate 33 and the gravity of the second and third paper transport driven rollers 36B and 37B attached to the second lower paper transport guide plate 33 is added. The gravity G is applied to the fourth rotating shaft 45 that pivotally supports the second lower paper conveyance guide plate 33 and the second link member 44, and this total gravity G is applied to the second lower paper conveyance guide. The reaction force of the component force Gx disassembled in the vertical direction of the plate 33 becomes the auxiliary force F, and the auxiliary force F applied to the fourth rotating shaft 45 attached to the second lower paper conveyance guide plate 33 is the smallest value. It becomes.

  On the other hand, the spring force B of the tension spring 49 is applied to the third rotating shaft 43 that pivotally supports the first link member 42 and the second link member 44, and this spring force B is large.

  As a result, when the second lower paper transport guide plate 33 is opened and positioned at the retracted position, the assisting force F to the second lower paper transport guide plate 33 can be reduced as much as possible.

  FIG. 3B shows a simplified view of the four-bar linkage mechanisms 34 and 41 to 45 in a state where the second lower sheet conveyance guide plate 33 is opened and positioned at the retracted position.

  In FIG. 3B, the first rotation shaft 34 is “b”, the second rotation shaft 41 is “b”, the third rotation shaft 43 is “c”, and the fourth If the rotation axis 45 is “d”, there is a “c” on the inside of the triangle “iron” that connects “b”, “b” and “d”. Mechanisms 34 and 41 to 45 are established.

  As described above, according to the paper transport device 30 according to the present invention, the upper and lower paper transport guide plates 31 and 33 for guiding the transport of the paper P are set above the paper transport path KR (or HR) set in the apparatus main body. And the upper and lower paper transport guide plates 31 and 33 with the paper transport members (36A, 37A) and (36B, 37B) attached to the upper and lower paper transport guide plates 31 and 33, respectively. In order to remove the jammed paper JP generated between the sheets 33, a lower sheet conveyance guide plate 33 that regulates the sheet conveyance path KR (or HR), a link support portion 40 and a spring support portion 47 provided in the apparatus main body. , And the tension springs 49 are incorporated so that the lower paper transport guide plate 33 is closed and the paper along the paper transport path KR (or HR). In the transfer operation position And the direction of opening by the total gravity G obtained by adding the weight of the lower paper transport guide plate 33 and the gravity of the paper transport members (36B, 37B) attached to the lower paper transport guide plate 33. A reverse assist force F is greatly applied to the lower paper transport guide plate 33, while the lower paper transport guide plate 33 is opened and located at a retracted position spaced downward from the paper transport operating position. In this case, since the auxiliary force F is not applied to the lower paper transport guide plate 33, the user can manually open the lower paper transport guide plate 33 when the user manually opens the lower paper transport guide plate 33. Since the plate 33 does not open vigorously downward, the burden on the user can be reduced, and when the user manually closes the lower paper transport guide plate 33, an operation to the lower paper transport guide plate 33 is performed. Power It can be reduced.

1 Image forming apparatus,
DESCRIPTION OF SYMBOLS 10 ... Paper feed part, 11 ... Paper feed stand, 12 ... Paper feed roller, 13 ... Separation roller, 14 ... Separation board,
20 ... Roller drive unit, 21 ... first motor, 22 ... gear train,
30: Paper transport device (paper feed side paper transport unit),
31 ... Upper sheet transport guide plate,
32 ... 1st lower paper conveyance guide plate, 33 ... 2nd lower paper conveyance guide plate,
34... First rotation shaft, 35A, 36A, 37A...
35B, 36B, 37B ... paper transport driven roller, 38 ... paper feed sensor,
40 ... link support part, 41 ... second rotating shaft, 42 ... first link member,
43 ... 3rd rotation axis, 44 ... 2nd link member, 45 ... 4th rotation axis,
47 ... Spring support, 48 ... Spring pin, 49 ... Tension spring,
50... Image forming section, 60... Paper discharge side paper transport section, 70.
P: paper, JP: jammed paper, KR: paper supply side paper conveyance path, HR: paper discharge side paper conveyance path.

Claims (1)

Upper and lower paper transport guide plates for guiding paper transport are provided separately on the upper and lower sides of the paper transport path set in the apparatus main body, and paper transport members are attached to the upper and lower paper transport guide plates, respectively. In order to remove jammed paper generated between the upper and lower paper transport guide plates, a lower paper transport guide plate is provided along the paper transport path with a pivot shaft provided in the apparatus body as a center. In the sheet conveying apparatus configured to rotate from the sheet conveying operation position to the retracted position spaced downward,
A first link member whose one end is pivotally supported by a link support disposed below the rotation shaft of the lower paper transport guide plate in the apparatus body;
A second link member having one end overlapped with the other end of the first link member and pivotally supported, and the other end opposite to the one end is pivotally supported by the lower sheet transport guide plate; ,
One end side is hooked to the spring support portion disposed below the link support portion in the apparatus body, and the other end side opposite to the one end side is hooked to the intersection of the first and second link members, A tension spring that urges the weight of the lower paper transport guide plate and the weight of the paper transport member attached to the lower paper transport guide plate to cancel each other;
A sheet conveying apparatus comprising:

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