JP5093002B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus such as a laser printer.

  In general, in an image forming apparatus such as a laser printer, after a developer image is transferred onto a sheet, the developer image is thermally fixed by a fixing device. At this time, it is known that the paper is curled (sludge of the paper) due to evaporation of moisture and contraction of the developer due to mechanical external force or heat. The occurrence of such curling lowers the stackability of the paper ejected on the paper ejection tray or the like. Therefore, the fixed paper is passed through the pair of conveying rollers to the image forming apparatus and mechanical external force is applied. Some curl amounts are reduced.

  However, the curl amount and curl direction of the paper vary depending on the material and thickness of the paper, so depending on the type of paper, the curl amount may be insufficiently reduced or the curl amount may be increased. There is. Therefore, in Patent Document 1, the curling amount can be reduced by changing the position of the conveying roller pair by swinging the conveying roller pair up and down in accordance with an arbitrary curling amount that varies depending on the material and thickness of the paper. An image forming apparatus that can be used is disclosed.

JP 7-48046 A (FIG. 1)

By the way, when the conveyance roller is configured to be linearly slidable, the position of the conveyance roller gear that rotates integrally with the conveyance roller is also displaced, so a power transmission mechanism is required to reliably transmit the driving force to the conveyance roller gear. It becomes.
SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus capable of reliably transmitting a driving force to a transport roller gear that rotates integrally with a transport roller in a configuration in which the transport roller can be displaced.

  In order to achieve the above object, an image forming apparatus of the present invention is an image forming apparatus that transfers and fixes a developer image onto a recording sheet, and includes an apparatus main body and a first position with respect to the apparatus main body. A pair of conveying rollers configured to be displaceable between the second position and conveying the recording sheet after fixing; and fixed to one of the pair of conveying rollers to rotate integrally, and the conveying roller A transport roller gear supported so as to be linearly slidable between a first position and a second position as viewed from the axial direction of the motor, a drive gear to which rotational driving force is input, the transport roller gear and the drive An intermediate gear meshing so as to be able to transmit power to the gear, one of the conveying roller gear and the driving gear, and the intermediate gear are held, and the intermediate gear is rotated around the axis of the conveying roller gear or the driving gear. And a gear holding member swingable, characterized by comprising a gear biasing member for biasing the intermediate gear toward the gear holding member held by not the drive gear or the conveyance roller gear.

  In the image forming apparatus configured as above, the intermediate gear is held by the gear holding member together with the conveying roller gear (or drive gear) and swingable around the axis of the conveying roller gear (or drive gear). It is biased toward the drive gear (or the transport roller gear) by the biasing member. As a result, even if the transport roller gear moves, the intermediate gear can always mesh with the transport roller gear and the drive gear so that power can be transmitted, so that the driving force is applied from the drive gear to the transport roller gear via the intermediate gear. Can be transmitted reliably.

  According to the image forming apparatus of the present invention, even if the transport roller is displaced, the intermediate gear can be engaged with the transport roller gear so that power can be transmitted between the transport roller gear and the drive gear. The driving force can be transmitted reliably.

<Overall configuration of laser printer>
Next, embodiments of the present invention will be described in detail with reference to the drawings as appropriate. In the drawings to be referred to, FIG. 1 is a cross-sectional view showing an overall configuration of a laser printer as an example of an image forming apparatus.

  Here, in the following description, the direction will be described with reference to the user who uses the laser printer. That is, in FIG. 1, the right side toward the paper surface is the “front” side, the left side toward the paper surface is the “rear” side, the back side toward the paper surface is the “right” side, and the front side toward the paper surface is “left”. ”Side. In addition, the vertical direction toward the page is the “vertical” direction.

  As shown in FIG. 1, a laser printer 1 includes a paper feeding unit 3 that supplies a sheet P as an example of a recording sheet, an exposure device 4, and a sheet in a main body housing 2 that forms a part of the apparatus main body. A process cartridge 5 for transferring a toner image (developer image) onto P and a fixing device 8 for thermally fixing the toner image on paper P are mainly provided.

  The paper feed unit 3 is disposed in the lower part of the main body housing 2 and is detachably attached to the main body housing 2, and a swingable paper provided in the paper feed tray 31. It mainly includes a pressing plate 32, a paper feed roller 33, a paper feed pad 34, paper dust removing rollers 35 and 36, and a registration roller 37 provided above the front side of the paper feed tray 31.

  In the paper feed unit 3, the paper P in the paper feed tray 31 is brought close to the paper feed roller 33 by the paper pressing plate 32, sent out by the paper feed roller 33 and the paper feed pad 34, and the paper dust removing rollers 35, 36. Then, after passing through the registration roller 37, each sheet is conveyed to the process cartridge 5 one by one.

  The exposure apparatus 4 is arranged at the upper part in the main body housing 2 and mainly includes a laser light emitting unit (not shown), a polygon mirror 41 that is rotationally driven, lenses 42 and 43, and reflecting mirrors 44, 45, and 46. In preparation. In the exposure apparatus 4, the laser light (see the chain line) based on the image data emitted from the laser light emitting part is reflected or passed through the polygon mirror 41, the lens 42, the reflecting mirrors 44 and 45, the lens 43 and the reflecting mirror 46 in this order. The surface of the photosensitive drum 61 is scanned at high speed.

  The process cartridge 5 is disposed below the exposure device 4 and is detachably mounted on the main body housing 2 through an opening formed when the front cover 21 provided on the front side of the main body housing 2 is opened. It has become. The process cartridge 5 includes a drum cartridge 6 and a developing cartridge 7.

  The drum cartridge 6 mainly includes a photosensitive drum 61, a transfer roller 62, and a charger 63, which are rotatably supported by the drum case 60, in a hollow drum case 60 constituting an outer frame.

  The developing cartridge 7 is configured to be detachably attached to the drum cartridge 6 (drum case 60). The developing cartridge 7 mainly includes a developing roller 71 and a supply roller 72 rotatably supported by the developing case 70 and a layer thickness regulating blade 73 in the developing case 70, and has a toner containing portion 74. Yes.

  In the process cartridge 5, the surface of the photosensitive drum 61 is uniformly charged by the charger 63 and then exposed by high-speed scanning of the laser light from the exposure device 4. Thereby, the potential of the exposed part is lowered, and an electrostatic latent image based on the image data is formed.

  At this time, the toner in the toner container 74 is supplied onto the supply roller 72 and is supplied onto the developing roller 71 by the sliding contact between the supply roller 72 and the developing roller 71. The toner supplied onto the developing roller 71 enters between the developing roller 71 and the layer thickness regulating blade 73 by the rotation of the developing roller 71 and is carried on the developing roller 71 as a thin layer having a constant thickness.

  The toner carried on the developing roller 71 is supplied to the electrostatic latent image on the photosensitive drum 61 when the developing roller 71 and the photosensitive drum 61 are in contact with each other. As a result, the electrostatic latent image is visualized and a toner image is formed on the photosensitive drum 61. Then, the sheet P is conveyed between the photosensitive drum 61 and the transfer roller 62, whereby the toner image on the photosensitive drum 61 is transferred onto the sheet P.

  The fixing device 8 is disposed behind the process cartridge 5 (on the downstream side in the conveyance direction of the paper P), and is disposed so as to face the heating roller 81 and sandwich the paper P between the heating roller 81 and the heating roller 81. The apparatus mainly includes a pressure roller 82 and a conveyance roller 83 that conveys the paper P after fixing. A detailed configuration of the fixing device 8 (around the conveyance roller 83) will be described later.

  The toner transferred onto the paper P is thermally fixed while the paper P passes between the heating roller 81 and the pressure roller 82. The paper P on which the toner image has been thermally fixed is discharged onto a paper discharge tray 23 formed on the upper surface of the main body housing 2 by the transport roller 83 and the pair of paper discharge rollers 22.

<Configuration around the transport roller>
Next, the configuration of the fixing device 8 (around the conveyance roller 83), which is a characteristic part of the present invention, will be described in detail. FIG. 2 is a perspective view of the fixing device in a state where the swinging portion is swung with respect to the fixed portion to expose the transport path, and FIG. 3A is a cross-sectional view of the fixing device when the transport roller is below. FIG. 4B is a sectional view of the fixing device when the conveying roller is at the upper side, FIG. 4 is a perspective view of the lower roller and the second holder, and FIG. FIG. 7 is a rear view of the fixing device at a certain time, and (b) is a rear view of the fixing device when a conveying roller is on the upper side. FIG. 6 is an exploded perspective view of the gear mechanism, FIG. 7A is a schematic diagram showing the fixing device when the conveying roller gear is below, and FIG. 6B is a fixing when the conveying roller gear is above. FIG. 8 is a schematic diagram showing the apparatus, and FIG. 8 is a schematic diagram showing how the swinging part is swung with respect to the fixed part.

  In this embodiment, the position shown in (a) of FIGS. 3, 5, and 7 (when the conveyance roller 83 is below) is defined as a “first position”, and the position shown in (b) (the conveyance roller 83 is (When it is above) is defined as “second position”. Here, when the transport roller 83 is above or below, the top and bottom are based on the top and bottom of the nip position where the pair of transport rollers 83 nip. Therefore, it is not necessary that the entire transport roller be above or below the one position. In this embodiment, the nip position of the transport roller 83 at the first position is lower than the nip position of the transport roller 83 at the second position.

  As shown in FIG. 2, the fixing device 8 includes a heating roller 81 (see FIG. 1), a pressure roller 82, a plurality of pairs of conveying rollers 83, and an example of a first holding member in a fixing case 80. A first holder 84, a second holder 85 as an example of a second holding member, and a gear mechanism 86 that transmits a driving force to the conveying roller 83 are mainly provided. In addition, in order to show each structure, in FIG. 2, the state which exposed 80 A of conveyance paths mentioned later is shown.

  The pair of transport rollers 83 includes an upper roller 83A and a lower roller 83B disposed below the upper roller 83A. The fixing device 8 includes a plurality (four pairs) of a pair of conveying rollers 83 arranged in the left-right direction (the width direction of the paper P).

The fixing case 80 is mainly composed of a fixing part 110 fixed to the main body housing 2 and constituting a part of the apparatus main body, and a swinging part 120 as an example of a roller holding member.
The fixing unit 110 supports the upper roller 83 </ b> A via the first holder 84.

  The swing part 120 supports the lower roller 83 </ b> B via the second holder 85. The swinging portion 120 swings with respect to the fixed portion 110 (device main body) by operating from an opening formed when the rear cover 24 (see FIG. 1) provided on the rear side of the main body housing 2 is opened. It is possible.

  When the swinging part 120 is swung from the state shown in FIG. 2 and the lower roller 83B and the upper roller 83A are nipped (when the swinging part 120 is closed), the fixed part 110 and the swinging part 120 are The facing portion is a conveyance path 80A for guiding the fixed sheet P toward the outside of the main body housing 2 (see FIG. 3). In the conveyance path 80 </ b> A, a guide for guiding the paper P is mainly configured by a plurality of guide ribs 111 provided in the fixing unit 110 and a plurality of guide ribs 121 and 122 provided in the swinging unit 120. Each guide rib 111, 121, 122 extends along the transport direction of the paper P.

  In this embodiment, the conveying path 80A (respective guide ribs 111, 121, 122) is exposed to the outside by swinging the swinging portion 120 from the state shown in FIG. 3A to the state shown in FIG. Can be made. Thereby, when the paper P is jammed in the transport path 80A, the paper P can be easily removed.

  As shown in FIGS. 2 and 3, the first holder 84 is individually provided corresponding to each pair of transport rollers 83 (each upper roller 83 </ b> A), and the upper roller 83 </ b> A (one of the pair of transport rollers 83). ) Is rotatably supported, and is supported by the fixing portion 110 of the fixing case 80 so as to be swingable. Specifically, the first holder 84 swings up and down around the shaft portion 112 as a fulcrum by pivotally supporting the shaft portion 112 provided on the fixed portion 110 on the front side (upstream side in the conveyance direction of the paper P). It is possible. Thereby, the upper roller 83A supported by the first holder 84 is also shown in the position (first position) shown in FIG. 3A and the position shown in FIG. 3B with respect to the fixed portion 110 (main body housing 2). It can swing up and down with respect to the position (second position).

  The first holder 84 is urged downward by a torsion spring 87 as an example of a roller urging member. Thereby, the upper roller 83A is urged toward the lower roller 83B. Further, the first holder 84 has projecting portions 841 projecting outward in the axial direction of the upper roller 83A on both the left and right wall surfaces. The protruding portion 841 restricts the upper roller 83A supported by the first holder 84 to the position shown in FIG. 3A by contacting the restricting portion 113 provided at the fixed portion 110 at the lower end.

  Further, the first holder 84 has a sheet guide portion 842 extending from the front side toward the peripheral surface of the upper roller 83A at the lower end portion. As shown in FIG. 3A, the sheet guide portion 842 protrudes from the guide rib 111 when the upper roller 83A is at the lower side, and separates the sheet P (see arrow) from the nip between the upper roller 83A and the lower roller 83B. Guide to location. On the other hand, as shown in FIG. 3B, when the upper roller 83A is on the upper side, it overlaps with the guide rib 111 when viewed from the axial direction of the upper roller 83A, and the paper P (see arrow) together with the upper rib 83A and the lower roller 83A. Guide to nip position with roller 83B.

  As shown in FIGS. 4 and 5, the second holder 85 rotatably supports the lower roller 83 </ b> B (the other of the pair of transport rollers 83) and is slidable to the swinging portion 120 of the fixing case 80. It is supported by. Specifically, the second holder 85 has a claw portion 851A of a gear cover 851 provided at the left end slidably engaged with the swinging portion 120, and a projection portion 852 provided at the right end on the swinging portion 120. By engaging with the provided long hole 123 (see FIG. 2), sliding movement is possible.

  As a result, the lower roller 83B supported by the second holder 85 is also slidable up and down between the position shown in FIG. 3A and the position shown in FIG. It has become. Each lower roller 83B is connected by a roller shaft 83C extending in the left-right direction, and rotates integrally when a driving force is transmitted from a gear mechanism 86 described later.

The second holder 85 has an operation portion 853 protruding rearward on the left side of the rear surface.
The transport roller 83 operates the operation portion 853 up and down from an opening formed when the rear cover 24 (see FIG. 1) is opened, so that the transport roller 83 is positioned relative to the main body housing 2 as shown in FIG. ) And a position shown in FIG. 5B (second position).

  The second holder 85 has two first support surfaces 854 and two second support surfaces 855 at different positions (heights) in the vertical direction at the bottom of the rear surface. The first support surface 854 and the second support surface 855 are formed as a continuous surface by an inclined surface 856 that is inclined downward from the left end of the first support surface 854 toward the right end of the second support surface 855.

The first support surface 854 is a surface that is supported from below by a position fixing member 88 described later when the lower roller 83B (second holder 85) is below (first position).
The second support surface 855 is a surface that is supported from below by the position fixing member 88 when the lower roller 83B (second holder 85) is in the upper position (second position), and is lower than the first support surface 854. Is located.

Here, a configuration for fixing the position of the transport roller 83 and an operation when the transport roller 83 is displaced will be described.
As shown in FIG. 5, a plate-like position fixing member 88 disposed at the same position as the operation unit 853 in the front-rear direction is provided on the rear surface of the swinging unit 120.

  In this position fixing member 88, the elongated hole 88 </ b> A extending in the left-right direction is engaged with the protrusion 124 provided on the rear surface of the swinging unit 120. The slide movement is possible. When the second holder 85 is in the lower position (first position), the position fixing member 88 and the operation unit 853 are aligned in the axial direction of the transport roller 83, so that the operation unit 853 is a stopper. Thus, the sliding movement of the position fixing member 88 to the right in the axial direction is restricted.

  Further, the position fixing member 88 is provided with a substantially trapezoidal support protrusion 88B that protrudes from the front surface (the back surface in FIG. 5). When the first support surface 854 or the second support surface 855 of the second holder 85 comes into contact with the support protrusion 88B from above, the position fixing member 88 supports the second holder 85 from below.

  When the transport roller 83 is displaced upward (from the position shown in FIG. 5A to the position shown in FIG. 5B), first, the operation unit 853 is lifted to slide the second holder 85 upward. Then, the lower roller 83B is moved upward. At this time, the upper roller 83A is pushed up by the lower roller 83B and swings upward. In this way, the transport roller 83 can be displaced upward (second position). After that, the second holder 85 (second support surface 855) is supported from below by the support protrusion 88B by sliding the position fixing member 88 toward the right side of FIG. As shown in (b), the transport roller 83 is fixed at the second position.

  When the transport roller 83 is displaced downward (from the position shown in FIG. 5B to the position shown in FIG. 5A), the position fixing member 88 is slid toward the left side in FIG. 5B. . Then, since the second holder 85 slides downward while the inclined surface 856 and the inclined surface (reference numeral omitted) of the support protrusion 88B are in sliding contact, the lower roller 83B also moves downward. The upper roller 83 </ b> A swings downward as the first holder 84 swings downward by the biasing force of the torsion spring 87. In this way, the transport roller 83 can be displaced downward (first position). At this time, as shown in FIG. 5A, the position fixing member 88 supports the second holder 85 (first support surface 854) from below by the support protrusion 88B and operates in the axial direction of the transport roller 83. It will be in the state where it lined up with part 853.

  As shown in FIGS. 6 and 7, the gear mechanism 86 mainly includes a transport roller gear 861, an intermediate gear 862, a drive gear 863, and a gear holder 130 as an example of a gear holding member.

  The transport roller gear 861 is a gear that is fixed to the left end of the lower roller 83B (roller shaft 83C) and rotates integrally with the lower roller 83B. Since the transport roller gear 861 is supported by the second holder 85 via the roller shaft 83C, when viewed from the axial direction of the transport roller 83 (lower roller 83B), the position shown in FIG. Position) and a position (second position) shown in FIG. 7B are slidable linearly up and down.

  The intermediate gear 862 is engaged with the conveyance roller gear 861 and the drive gear 863 so that power can be transmitted. The operation of the intermediate gear 862 will be described later.

  The drive gear 863 is rotatably supported by the fixed portion 110 (device main body), and meshes with the intermediate gear 862 and a heating roller gear 811 that rotates integrally with the heating roller 81 (see FIG. 1). A rotational driving force from a driving source (not shown) provided in the main body housing 2 is input to the driving gear 863 via a transmission gear and a heating roller gear 811 (not shown). The driving force input to the drive gear 863 is input to the transport roller gear 861 via the intermediate gear 862, and rotates the transport roller 83 (lower roller 83B).

  The gear holder 130 holds the transport roller gear 861 and the intermediate gear 862 such that the distance between the axes is constant. Specifically, the gear holder 130 holds the transport roller gear 861 rotatably by engaging a shaft portion 861A of the transport roller gear 861 in a cylindrical portion 132 described later, and the shaft portion 131 protruding from the right surface has the intermediate gear 862. The intermediate gear 862 is rotatably held by engaging with a recess 862A provided at the center of rotation. Further, the gear holder 130 holds the intermediate gear 862 such that the intermediate gear 862 can swing around the conveyance roller gear 861.

  The gear holder 130 has a cylindrical portion 132 that extends coaxially with the shaft portion 861A of the transport roller gear 861 from the left surface toward the outside in the left-right direction. A projecting portion 133 extending in the radial direction of the cylindrical portion 132 is formed on the outer peripheral surface 132 </ b> A of the cylindrical portion 132.

  As shown in FIG. 4, the rear portion of the gear holder 130 and the transport roller gear 861 are covered with a gear cover 851 provided on the second holder 85 in a state where the gear holder 130 is supported by the second holder 85. In the gear holder 130, the cylindrical portion 132 is pivotally supported in a circular hole portion 851 </ b> B provided in the gear cover 851. A fan-shaped recess 851C that engages with the protrusion 133 is formed on the inner peripheral surface of the hole 851B. As shown in FIGS. 7A and 7B, the recess 851 </ b> C has a vertical length longer than the vertical length of the protrusion 133, and thus the protrusion 133 moves in the circumferential direction of the cylindrical portion 132. (Oscillation) is allowed.

  A spring mounting portion 134 that protrudes downward is provided at the lower end of the gear holder 130. Further, a spring mounting portion 851D is provided at a position facing the spring mounting portion 134 in the front-rear direction at the lower end of the gear cover 851 of the second holder 85. A coil spring 89 as an example of a gear urging member is disposed between the spring attachment portions 134 and 851D. The coil spring 89 urges the gear holder 130 to urge the intermediate gear 862 toward the drive gear 863 that is not held by the gear holder 130.

  In the gear mechanism 86 configured as described above, when the transport roller 83 is displaced from the position shown in FIG. 7A to the position shown in FIG. 7B, the transport roller gear 861 linearly moves upward together with the lower roller 83B. Move the slide. At this time, the intermediate gear 862 swings relative to the transport roller gear 861 (shaft portion 861 </ b> A) in a clockwise direction so as to be pushed by the drive gear 863, but is biased by the drive gear 863 by the coil spring 89. Therefore, the engagement with the drive gear 863 is maintained.

  On the other hand, when the transport roller 83 is displaced from the position shown in FIG. 7B to the position shown in FIG. 7A, the transport roller gear 861 slides linearly together with the lower roller 83B. At this time, the intermediate gear 862 is oscillated relative to the conveying roller gear 861 (shaft portion 861 </ b> A) by the coil spring 89 in a counterclockwise direction and is urged to the drive gear 863. The occlusion is maintained.

Note that the meshing between the transport roller gear 861 and the intermediate gear 862 is maintained by the gear holder 130 that keeps the distance between the axes of the transport roller gear 861 and the intermediate gear 862 constant.
As described above, even if the transport roller gear 861 moves, the intermediate gear 862 can always mesh with the transport roller gear 861 and the drive gear 863 so that power can be transmitted. Can be reliably transmitted to the transport roller gear 861.

  In the present embodiment, the conveyance roller gear 861 and the intermediate gear 862 are supported by the swinging portion 120 of the fixing case 80 via the gear holder 130 and the second holder 85. Therefore, as shown in FIG. 8, the meshing between the intermediate gear 862 and the drive gear 863 is released by swinging the swinging portion 120 so as to expose the conveyance path 80 </ b> A (see FIG. 3). ing.

  At this time, in the intermediate gear 862, the protrusion 133 of the gear holder 130 abuts one end of the recess 851C of the second holder 85, so that the counterclockwise swinging by the coil spring 89 is restricted to a predetermined position. . Similarly, the swinging downward of the upper roller 83A is regulated at a predetermined position by the protrusion 841 of the first holder 84 coming into contact with the regulating part 113 (see FIG. 3A). Accordingly, when the swinging portion 120 is closed, the intermediate gear 862 and the drive gear 863 can be satisfactorily engaged with each other, and the upper roller 83A and the lower roller 83B can be nipped well.

According to the above, the following effects can be obtained in the present embodiment.
The conveyance roller gear 861 and the intermediate gear 862 are held and the intermediate gear 862 is swingable about the axis of the conveyance roller gear 861 and the intermediate gear 862 is urged toward the drive gear 863 not held by the gear holder 130. Since the coil spring 89 is provided, even if the transport roller 83 (transport roller gear 861) is displaced, the intermediate gear 862 can always mesh with the transport roller gear 861 and the drive gear 863 so that power can be transmitted. . Thereby, the driving force from the drive gear 863 can be reliably transmitted to the transport roller gear 861 (transport roller 83).

  A protruding portion 133 is formed on the outer peripheral surface 132A of the cylindrical portion 132 of the gear holder 130, engages with the protruding portion 133 in the hole portion 851B of the second holder 85, and allows the protruding portion 133 to move in the circumferential direction of the cylindrical portion 132. Since the recess 851C is formed, the position of the gear holder 130 (intermediate gear 862) can be restricted to a predetermined position.

  As a result, the intermediate gear 862 is not urged against the drive gear 863 with an unnecessarily strong force, so that the gears 861, 862, and 863 can rotate satisfactorily. Further, since the position of the intermediate gear 862 does not move greatly when the swinging portion 120 is opened (see FIG. 2), when the swinging portion 120 is closed after the jammed paper P is removed, The drive gear 863 can be meshed with the drive gear 863, and the swinging portion 120 can be satisfactorily closed.

  Since the second holder 85 supports the lower roller 83B so that the lower roller 83B can be slid up and down with respect to the swinging portion 120, the lower roller 83B (conveying roller 83) can be compared with a configuration in which the lower roller 83B can swing. The amount of movement can be increased. As a result, the curl reduction effect by changing the position of the transport roller 83 can be increased.

  In addition, since the second holder 85 has the protruding operation portion 853 that is operated during the slide movement, the transport roller 83 can be easily displaced. Further, since the position fixing member 88 (supporting protrusion 88B) that supports the second holder 85 from below when the lower roller 83B is on the upper side is provided, the second holder 85 (conveying roller 83) can be stably supported. Can do.

  Further, in order to displace the transport roller 83 upward (second position), the operation unit 853 is operated to slide the second holder 85 upward, and the position fixing member 88 is supported by the second support projection 88B. Since the second support surface 855 of the holder 85 needs to be slid to a position where the second support surface 855 is supported from below, the transport roller 83 can be fixed downward (first position) unless operated by the user.

  The first holder 84 extends from the upstream side in the transport direction of the sheet P toward the peripheral surface of the upper roller 83A, and the sheet guide portion 842 that protrudes from the guide rib 111 when the upper roller 83A is in the lower position (first position). Therefore, when the transport roller 83 is at the lower side, the paper P can be smoothly transported to the nip position of the transport roller 83 by guiding the paper P along the sheet guide portion 842.

When the transport roller 83 is in the upper position (second position), the paper P can be smoothly transported to the nip position of the transport roller 83 by guiding the paper P along the guide rib 111 (and the sheet guide portion 842). it can.
As described above, according to the present embodiment, the paper P can be smoothly transported to the nip position of the transport roller 83 in the configuration in which the transport roller 83 is displaced. In addition, it is possible to suppress the paper P from colliding with the conveyance roller 83, the guide rib 111, or the like.

  A plurality of pairs of transport rollers 83 are arranged in the width direction of the paper P, and the first holder 84 is individually provided corresponding to each pair of transport rollers 83. Each upper roller 83 </ b> A can individually swing according to the unevenness. Thereby, the paper P can be transported more smoothly and satisfactorily.

  Since the upper roller 83A supported by the first holder 84 is provided with a torsion spring 87 that urges the upper roller 83A toward the lower roller 83B, the upper roller 83A and the lower roller 83B are always pressed against each other even if the transport roller 83 is displaced. Can be made. Thereby, the paper P can be reliably conveyed.

  The first holder 84 has a protruding portion 841 that protrudes outward in the axial direction of the upper roller 83A, and the fixing portion 110 (device main body) contacts the protruding portion 841 to restrict the upper roller 83A to the first position. 113, the position of the upper roller 83A can be restricted to a predetermined position. As a result, the upper roller 83A does not swing too much downward, so that, for example, the upper roller 83A can be prevented from being too pressed against the lower roller 83B. Further, after the swinging portion 120 is opened (see FIG. 2) and the jammed paper P is removed, the upper roller 83A and the lower roller 83B can be nipped well when the swinging portion 120 is closed. The moving part 120 can be satisfactorily closed.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to above-described embodiment. About a concrete structure, it can change suitably in the range which does not deviate from the meaning of this invention.

  In the above-described embodiment, the configuration in which the first holder 84 is individually provided corresponding to each pair of the transport rollers 83 (each upper roller 83A) is shown, but the present invention is not limited to this. For example, as in the first holder 84 ′ shown in FIG. 9, each pair of transport rollers 83 (each upper roller 83 </ b> A) may be integrally supported. Although not shown, the first holder 84 'is supported so as to be swingable up and down with respect to the fixed portion 110, and is biased downward by a roller biasing member (such as a torsion spring). . As a result, each upper roller 83A can also swing up and down and is biased toward the lower roller 83B.

  According to this, it is possible to easily assemble the first holder 84 ′ as a component to the fixing portion 110, and to make the force of each upper roller 83A urged by the corresponding lower roller 83B substantially uniform. P can be stably conveyed.

  Incidentally, the first holder 84 ′ is provided with a plurality of rib-like sheet guide portions 842 ′ extending from the front side toward the peripheral surface of the upper roller 83 </ b> A at the lower end portion, aligned in the left-right direction. The sheet guide portion 842 ′ configured in this manner swings up and down together with the upper roller 83A, and the upper roller 83A and the lower roller 83B nip the paper P when the upper roller 83A is in either the upper or lower position. Guide to the nip position. It should be noted that a plurality of guide ribs may be provided on the fixed portion 110 so that the sheet guide portion 842 'protrudes from the guide rib when at least the upper roller 83A is located below.

  In the above-described embodiment, the first holder 84 (first holding member) pivotally supports the shaft portion 112 provided on the fixed portion 110, and the configuration in which the shaft portion 112 can be swung up and down is shown. However, the present invention is not limited to this. For example, the first holding member may be provided with a shaft portion that protrudes outward in the axial direction of the conveying roller to be supported, and the shaft body may be supported by the apparatus main body.

  In the above-described embodiment, the sheet guide portion 842 is configured to protrude from the guide rib 111 when the upper roller 83A (conveying roller supported by the first holding member) is below (first position). However, the present invention is not limited to this. For example, the sheet guide unit may be configured to protrude from a guide (such as a wall constituting the conveyance path) that constitutes the conveyance path even when the conveyance roller is in the second position. In this case, the protruding amount of the sheet guide portion when the conveying roller is in the first position is different from the protruding amount of the sheet guide portion when the conveying roller is in the second position.

  In the above-described embodiment, an example in which the torsion spring 87 is employed as an example of the roller urging member has been described. However, the present invention is not limited thereto, and for example, a coil spring or a leaf spring may be employed.

  In the above-described embodiment, an example in which the guide configuring the conveyance path 80A is the plurality of guide ribs 111 is illustrated. However, the present invention is not limited to this, for example, a guide surface (a wall configuring the conveyance path). May be.

  In the above-described embodiment, the example in which the first holder 84 is individually provided corresponding to each upper roller 83A and the example in which the first holder 84 ′ integrally supports the plurality of upper rollers 83A are shown. The invention is not limited to this. For example, a configuration may be employed in which four pairs of transport rollers and two first holding members are provided, and each first holding member supports two pairs of transport rollers (two upper rollers).

  In the above-described embodiment, the configuration in which the pair of transport rollers 83 moves up and down between the first position and the second position has been described. However, the present invention is not limited to this, and for example, a pair of transport rollers May be configured to move back and forth between the first position and the second position. In the embodiment described above, an example in which a pair of transport rollers 83 are arranged in the width direction of the paper P and four pairs are provided is shown. However, in the present invention, the number of the pair of transport rollers is not particularly limited, and a plurality of pairs of transport rollers 83 Or just one pair.

  The configurations and shapes of the first holder 84 and the second holder 85 shown in the above-described embodiment are examples, and the present invention is not limited to this. That is, the first holding member and the second holding member of the present invention can be configured and shaped to exhibit the same effects as the first holder 84 and the second holder 85 described above without departing from the spirit of the present invention. It can be changed as appropriate.

  In the above-described embodiment, the configuration in which the rotational driving force is input to the driving gear 863 via another gear (the heating roller gear 811) has been described, but the present invention is not limited to this, and is provided, for example, in the apparatus main body. Alternatively, the rotational driving force may be directly input to the driving gear from the driving source.

  In the above-described embodiment, an example in which the coil spring 89 is employed as an example of the gear urging member has been described. However, the present invention is not limited thereto, and for example, a torsion spring or a leaf spring may be employed.

  In the above-described embodiment, the plurality of guide ribs 121 and 122 are exemplified as a part of the conveyance path 80A formed by the swinging unit 120 (roller holding member). However, the present invention is not limited to this, and for example, the fixing unit 110 The wall surface of the oscillating portion 120 facing the surface may constitute a part of the transport path.

  Note that the phrase “the roller holding member supports the conveyance roller that rotates integrally with the conveyance roller gear” is not limited to a configuration in which the roller holding member directly supports the conveyance roller that rotates integrally with the conveyance roller gear. That is, as in the above-described embodiment, the transport roller (lower roller 83B) in which the roller holding member (swinging portion 120) rotates integrally with the transport roller gear is passed through the second holding member (second holder 85) or the like. Indirect support is also included.

  In the embodiment described above, a configuration is shown in which the conveying path 80A (guide ribs 111, 121, 122) can be exposed by the swinging portion 120 (roller holding member) swinging with respect to the fixed portion 110 (device main body). However, the present invention is not limited to this. That is, the present invention can be applied to a configuration in which the roller holding member does not swing with respect to the apparatus main body.

  In the above-described embodiment, the gear holder 130 holds the transport roller gear 861 and the intermediate gear 862 and is supported by the swing part 120, and the drive gear 863 is supported by the fixed part 110. It is not limited to. For example, as shown in FIG. 10A, the gear holder 130 ′ holds the drive gear 863 and the intermediate gear 862 and is supported by the fixed portion 110 (the apparatus main body), and the transport roller gear 861 moves the swing portion 120 (the roller holding member). ) May be supported. In this case, the intermediate gear 862 can swing around the axis of the drive gear 863, and is further biased toward the transport roller gear 861 that is not held by the gear holder 130 ′ by the coil spring 89.

  In such a configuration, as shown in FIG. 10B, the swinging portion 120 is swung so as to expose the transport path 80A (see FIG. 3), so that the transport roller gear 861 and the intermediate gear 862 are separated. The tooth will be disengaged.

  In the above-described embodiment, the protruding portion 133 is formed in the cylindrical portion 132 provided in the gear holder 130, and the recess 851C is formed in the hole portion 851B provided in the second holder 85. However, the present invention is limited to this. Is not to be done. For example, as shown in FIGS. 10 (a) and 10 (b), it extends in the radial direction of the cylindrical portion 132 of the gear holder 130 ′ on the inner peripheral surface of the hole 115 provided in the gear cover 114 of the fixed portion 110 (device main body). A protrusion 135 is formed on the outer peripheral surface of the cylindrical portion 132 that extends coaxially with the axis of the drive gear 863 and engages with the protrusion 116 to allow relative movement of the protrusion 116 in the circumferential direction of the cylindrical portion 132. May be formed.

  The configurations and shapes of the swinging portion 120 and the gear holder 130 shown in the above-described embodiment are examples, and the present invention is not limited to this. That is, the roller holding member and the gear holding member of the present invention can be appropriately changed without departing from the spirit of the present invention as long as the configuration and shape exhibit the same functions as those of the swinging unit 120 and the gear holder 130 described above. Can do.

  In the above-described embodiment, the configuration in which the conveyance roller 83 and the conveyance roller gear 861 are provided in the fixing device 8 is shown. However, the present invention is not limited to this, and for example, the conveyance roller and the conveyance roller gear are in the conveyance direction of the fixing device. A configuration provided separately from the fixing device may be provided on the downstream side. The present invention is not limited to a conveyance roller that conveys a recording sheet after fixing, and can be widely applied to a conveyance roller configured to be displaceable.

  In the above-described embodiment, the paper P such as a thick paper, a postcard, and a thin paper is shown as an example of the recording sheet. However, the present invention is not limited to this, and may be an OHP sheet, for example.

  In the above-described embodiment, the laser printer 1 that forms a single-color image is shown as an example of the image forming apparatus. However, the present invention is not limited to this, and for example, a copier, a multifunction machine, or a multicolor image that forms a single-color image. A color printer, a color copying machine, a color complex machine, or the like may be used. In addition, the image forming apparatus of the present invention is not limited to the one that exposes the photosensitive drum 61 (photosensitive body) with laser light. For example, the image forming apparatus emits light from an LED (light emitting diode), an EL (electroluminescence) element, or a phosphor. The photosensitive member may be exposed to light that is emitted.

1 is a cross-sectional view illustrating an overall configuration of a laser printer as an example of an image forming apparatus. FIG. 6 is a perspective view of the fixing device in a state in which a swing path is swung with respect to a fixed section to expose a conveyance path. (A) is a cross-sectional view of the fixing device when the conveying roller is below, and (b) is a cross-sectional view of the fixing device when the conveying roller is above. It is a perspective view of a lower roller and a 2nd holder. (A) is a rear view of the fixing device when the conveying roller is below, and (b) is a rear view of the fixing device when the conveying roller is above. It is a disassembled perspective view of a gear mechanism. (A) is a schematic diagram showing the fixing device when the conveying roller gear is below, and (b) is a schematic diagram showing the fixing device when the conveying roller gear is above. It is a schematic diagram which shows a mode that a rocking | swiveling part is rock | fluctuated with respect to a fixing | fixed part. It is a perspective view of a fixing device provided with the 1st holder concerning a modification. (A) is a schematic diagram which shows the fixing device provided with the gear mechanism concerning a modification, (b) is a schematic diagram which shows a mode that a rocking | fluctuation part is rock | fluctuated with respect to a fixed part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laser printer 2 Main body housing | casing 80A Conveyance path 83 Conveyance roller 83A Upper roller 83B Lower roller 85 Second holder 88 Position fixing member 89 Coil spring 110 Fixing part 120 Swing part 121 Guide rib 122 Guide rib 130 Gear holder 132 Cylindrical part 132A Outer peripheral surface 133 Projection Portion 851B Hole portion 851C Concave portion 853 Operation portion 861 Transport roller gear 861A Shaft portion 862 Intermediate gear 863 Drive gear P Paper

Claims (5)

An image forming apparatus for transferring and fixing a developer image on a recording sheet,
The device body;
A pair of conveying rollers configured to be displaceable between a first position and a second position with respect to the apparatus main body, and conveying a recording sheet after fixing;
It is fixed to one of the pair of transport rollers and rotates integrally, and is supported so as to be linearly slidable between a first position and a second position when viewed in the axial direction of the transport rollers. Transport roller gear,
A driving gear to which rotational driving force is input;
An intermediate gear engaged so as to be able to transmit power between the transport roller gear and the drive gear;
A gear holding member that holds either the transport roller gear or the drive gear and the intermediate gear, and allows the intermediate gear to swing around the transport roller gear or the drive gear;
An image forming apparatus comprising: a gear urging member that urges the intermediate gear toward the driving gear or the transport roller gear that is not held by the gear holding member. Supports a conveyance roller that rotates integrally with the conveyance roller gear, forms a part of a conveyance path that guides a recording sheet after fixing, and allows the conveyance path to be exposed by swinging with respect to the apparatus main body. A roller holding member
The gear holding member is supported by the roller holding member while holding the transport roller gear and the intermediate gear,
The drive gear is supported by the apparatus main body,
The image forming apparatus according to claim 1, wherein the intermediate gear and the drive gear are disengaged when the roller holding member is swung so as to expose the conveyance path. apparatus. Supports a conveyance roller that rotates integrally with the conveyance roller gear, forms a part of a conveyance path that guides a recording sheet after fixing, and allows the conveyance path to be exposed by swinging with respect to the apparatus main body. A roller holding member
The gear holding member holds the drive gear and the intermediate gear and is supported by the apparatus main body,
The transport roller gear is supported by the roller holding member,
2. The image forming apparatus according to claim 1, wherein when the roller holding member is swung so as to expose the conveyance path, the engagement between the conveyance roller gear and the intermediate gear is disengaged. apparatus. The gear holding member has a cylindrical portion extending coaxially with an axis of the conveying roller gear or the driving gear to be held,
The apparatus main body has a circular hole portion that pivotally supports the cylindrical portion,
On the outer peripheral surface of the cylindrical portion and the inner peripheral surface of the hole portion, a protruding portion that extends in the radial direction of the cylindrical portion is formed on one side, and on the other side, the protruding portion engages with the protruding portion, and in the circumferential direction of the cylindrical portion The image forming apparatus according to claim 2, wherein a recess that allows relative movement of the protrusion is formed. A second holding member that directly supports a conveying roller that rotates integrally with the conveying roller gear, and that is supported so as to be slidable up and down with respect to the roller holding member, and has a protruding operation portion that is operated during sliding movement;
When the conveying roller supported by the second holding member is on the upper side, the position of the conveying roller between the position where the second holding member is supported from below and the position where the conveying roller is aligned with the operation unit in the axial direction of the conveying roller. The image forming apparatus according to claim 2, further comprising a position fixing member configured to be slidable in an axial direction.

Images