JP5381750B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus including a discharge roller (drive roller) for discharging a recording sheet to the outside of an apparatus housing and two pinch rollers.

  In an image forming apparatus having a pair of paper discharge rollers for discharging paper (recording sheet) after image formation to the outside of the apparatus housing, the two paper discharge roller pairs are arranged side by side along the paper discharge direction. There is known a configuration in which a pinch roller is opposed to and pressed against a driving roller to discharge a sheet while curling the sheet (see, for example, Patent Document 1).

  In the image forming apparatus described in Patent Document 1, a leaf spring is provided that urges a holding member that holds two pinch rollers toward the drive roller. The leaf spring includes a holding portion that extends in the paper discharge direction to hold the pinch roller, and a base that is bent from the holding portion and extends in a direction substantially perpendicular to the paper discharge direction. By making the pinch roller displaceable in the paper discharge direction, the pinch roller is reliably brought into contact with the drive roller.

JP 2000-56530 A

  In general, the curl amount of paper after image formation varies depending on the type of paper to be used, and therefore it is desirable that the curl removal amount can be adjusted by adjusting the contact pressure of the pinch roller. For example, in the image forming apparatus of Patent Document 1, when using a sheet with a small curl amount after the image forming process, the pinch roller is moved from the drive roller by moving the position of the leaf spring in order to reduce the contact pressure of the pinch roller. The distance is set so that only one pinch roller contacts the driving roller.

  However, according to the configuration of Patent Document 1, for example, when a thick paper having high bending rigidity passes in a state in which only one pinch roller is in contact with the drive roller, the sheet discharge direction is caused by elastic deformation of the leaf spring. There is a possibility that the stable posture cannot be maintained because the pinch roller shakes and a gap is generated between the drive roller and the pinch roller.

  Therefore, it is desired to suppress variation in the curl amount of discharged paper by maintaining a stable posture of the pinch roller even in a state where only one pinch roller is in contact with the drive roller. . The present inventor paid attention to such a technical problem in the course of research to provide an image forming apparatus capable of achieving smooth discharge by good curl removal of a recording sheet and good stackability after discharge. The present invention has been invented.

An image forming apparatus according to an aspect of the present invention includes a housing, an image forming portion that is provided inside the housing and forms an image on a recording sheet, a driving roller, and a sheet at a position facing the driving roller. A discharge roller unit that includes two pinch rollers arranged side by side in the discharge direction and a holding member that holds the two pinch rollers, and discharges the recording sheet conveyed from the image forming unit to the outside of the housing. An urging member that urges the holding member toward the drive roller, an operation mode of the discharge roller unit, a double mode in which both the two pinch rollers are pressed against the drive roller, and the two A switching member that switches between a single mode in which only one of the pinch rollers is pressed against the drive roller, and a sheet of the holding member in the single mode. And a regulating means for locking the discharge direction position, the retaining member is rotatably supported by the drive roller and parallel to the axis around realizing the double-mode a first position to realize the single mode The switching member is displaceable to a second position, and the switching member is rotatably supported around an axis parallel to the drive roller, and a single mode position for realizing the single mode and a double mode for realizing the double mode. The holding member is rotated in conjunction with the rotation of the switching member, and when the switching member is switched to the single mode position, the holding member is moved to the first position. When the switching member is switched to the double mode position, the holding member is arranged at the second position, and the restricting means is a contact portion provided on the switching member. The holding member against the biasing force of the biasing member, the contact portion of the switching member in the single mode position And a part of the main body frame restricts the rotation of the holding member .

  According to the image forming apparatus configured as described above, even when the operation mode of the discharge roller unit that can be switched in accordance with the change of the type of the recording sheet is set to “single mode”, the position of the holding member is Since it is stable without shaking in the sheet discharge direction, good curl removal performance of the recording sheet is exhibited.

1 is a diagram illustrating a schematic configuration of a color printer as an example of an image forming apparatus according to an embodiment of the present disclosure. It is a perspective view which shows schematic structure around a discharge roller unit. It is a perspective view which shows arrangement | positioning of the discharge roller unit except a drive roller, and a switching member. It is a disassembled perspective view which shows the structure of the discharge roller unit except a drive roller, and a switching member. It is sectional drawing which shows the state at the time of double mode switching. It is sectional drawing which shows the state at the time of single mode switching.

  Next, an embodiment of the present invention will be described in detail with reference to the drawings as appropriate. In the following description, the schematic configuration of the color printer 1 as an example of the image forming apparatus will be described first, and then the details of the configuration relating to the characteristic part of the present invention will be described.

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

<Schematic configuration of laser printer>
As shown in FIG. 1, the color printer 1 mainly includes a paper feed unit 3, an image forming unit 4, and a conveyance unit 5 in a main body housing 2.

  The paper feed unit 3 is provided at a lower portion in the main body housing 2 and mainly includes a paper feed tray 31 and a paper feed mechanism 32. A sheet S as an example of a recording sheet stored in the sheet feeding tray 31 is supplied to the image forming unit 4 by the sheet feeding mechanism 32.

  The image forming unit 4 is configured to form an image on the paper S, and mainly includes an exposure device 41, four process units 42, a transfer unit 43, and a fixing device 44.

  The exposure device 41 is provided in the upper part of the main body housing 2 and includes a laser light source, a polygon mirror, a lens, a reflecting mirror, and the like (not shown). Laser light emitted from the laser light source based on the image data is reflected by a polygon mirror or a reflecting mirror, passes through a lens, and is scanned at a high speed on the surface of each photosensitive drum 42A.

  The process unit 42 is arranged side by side between the paper feed tray 31 and the exposure device 41, and mainly includes a photosensitive drum 42A, a charger 42B, a developing roller (not shown), a supply roller, a toner container, and the like. Yes. Each process unit 42 differs only in the color of the toner accommodated in the toner accommodating portion, and the configuration is substantially the same.

  The transfer unit 43 is provided between the paper feed tray 31 and the process unit 42, and includes an endless transport belt 43C stretched between a driving roller 43A and a driven roller 43B, and four transfer rollers 43D. In preparation. The outer surface of the transport belt 43C is in contact with each photoconductor drum 42A, and the transfer roller 43D is disposed inside the transport belt 43C so as to sandwich the transport belt 43C with each photoconductor drum 42A.

  The fixing device 44 is provided at the rear of the process unit 42 and mainly includes a heating roller 44A and a pressure roller 44B that is disposed to face the heating roller 44A and presses the heating roller 44A.

  In the image forming unit 4, the surface of the photosensitive drum 42 </ b> A is uniformly charged by the charger 42 </ b> B, and then exposed by the laser beam (see the chain line) from the exposure device 41, so that the photosensitive drum 42 </ b> A is exposed on the photosensitive drum 42 </ b> A. An electrostatic latent image based on the image data is formed. Then, the toner in the toner container is supplied to the electrostatic latent image on the photosensitive drum 42A via the supply roller and the developing roller, so that the electrostatic latent image is visualized and the toner on the photosensitive drum 42A. A toner image is formed.

  Thereafter, the sheet S supplied from the sheet feeding unit 3 to the image forming unit 4 is conveyed between the photosensitive drum 42A and the conveying belt 43C (transfer roller 43D), and thus formed on each photosensitive drum 42A. The transferred toner images are sequentially superimposed on the paper S and transferred. Then, the sheet S is conveyed between the heating roller 44A and the pressure roller 44B, whereby the toner image transferred onto the sheet S is thermally fixed, and an image is formed on the sheet S.

  The transport unit 5 mainly includes a transport path 51, a pair of transport rollers 52, and a discharge roller unit 100.

  The conveyance path 51 is a path (recording sheet conveyance path) for guiding the sheet S conveyed from the image forming unit 4 (exit of the fixing device 44) toward the discharge roller unit 100, and the rear part in the main body housing 2. In FIG. 1, it extends substantially up and down and gently curves forward on the upper end side. The transport roller 52 is a roller that is provided in the transport path 51 and transports the paper S in the transport path 51. The discharge roller unit 100 is a mechanism that discharges the sheet S conveyed from the image forming unit 4 to the outside of the main body housing 2. Details of the structure around the discharge roller unit 100 will be described later.

  In the transport unit 5, the paper S carried out from the image forming unit 4 is transported along the transport path 51 by the transport roller 52, and discharged by the discharge roller unit 100 on the outside (upper surface) of the main body housing 2. It is discharged onto the tray 22.

<Structure around the discharge roller unit>
Next, the discharge roller unit 100 and its peripheral structure in the transport unit 5 will be described in detail with reference mainly to FIGS. FIG. 2 shows the overall arrangement of the transport unit 5, and FIGS. 3 and 4 show the main components of the mechanism for discharging the paper S to the outside of the main body housing 2 (an example of the discharge roller unit 100 and the urging member). A configuration example of the coil spring 130 and the switching member 120) will be specifically illustrated.

  As shown in FIG. 2, four discharge roller units 100 are provided at intervals in the left-right direction (the width direction of the discharged paper S), and each mainly includes a drive roller 101 and a drive roller 101. 2, two pinch rollers 102 and 103 arranged side by side in the paper S discharge direction, and a holding member 110 that holds the pinch rollers 102 and 103.

  The four drive rollers 101 are connected by a drive shaft portion 101S, and a drive gear portion 101G is provided at the left end portion of the drive shaft portion 101S. When the driving force of a motor (not shown) provided in the main body housing 2 is input to the driving gear portion 101G, the driving roller 101 is driven.

  The pinch roller 102 on the downstream side is configured integrally with two rollers arranged coaxially (see also FIG. 3). Further, the upstream pinch roller 103 is configured integrally with three rollers arranged coaxially. Each of the pinch rollers 102 and 103 is rotatably held by the holding member 110.

  As shown in FIGS. 3 and 4, the holding member 110 includes a base portion 111, a downstream bearing portion 112, an upstream bearing portion 113, an arm portion 114, an engaged portion 115, a shaft portion 116, and a guide portion 117. These are configured integrally.

  The downstream bearing portion 112 is formed so as to protrude upward from the left and right sides of the front portion of the base portion 111, and rotatably supports the downstream pinch roller 102. The upstream bearing portion 113 is disposed adjacent to the downstream side of the downstream bearing portion 112 (upstream side in the paper discharge direction), and rotatably supports the upstream pinch roller 103. The downstream bearing portion 112 and the upstream bearing portion 113 together with the base portion 111 constitute a “holder portion” that holds the two pinch rollers 102 and 103.

  The arm portion 114 is a plate-like portion having a rectangular surface with the left-right direction as the width direction and the up-down direction as the longitudinal direction, and is formed to extend downward from the rear end portion of the base portion 111. . The lower end portion of the arm portion 114 has a shape that is bent substantially vertically toward the rear, and forms a plate-like engaged portion 115 that protrudes rearward.

  The upper surface 115S of the engaged portion 115 has a shape in which a substantially central portion in the front-rear direction is raised, and a contact action portion 122 of a switching member 120 described later can be engaged. In addition, the corner 114S connected to the engaged portion 115 at the lower end of the front surface of the arm portion 114 is chamfered in a curved shape, and a part of the body frame 140 (regulation) is operated during single mode operation to be described later. The surface abuts against the surface 140S) (see FIGS. 5 and 6).

  The shaft 116 protrudes outward from the left and right sides of the base 111 below the downstream bearing 112 and the upstream bearing 113, and as shown in FIGS. 5 and 6, It is loosely fitted in a groove portion 145G of a support portion 145 fixed to the main body frame 140. Therefore, the holding member 110 holding the pinch rollers 102 and 103 can be rotated around the shaft portion 116, and the shaft portion 116 as the rotation shaft can be displaced in the vertical direction along the groove portion 145G. .

  The shaft portion 116 is disposed at a position slightly shifted to the upstream side from the center in the paper discharge direction of the holder portion (downstream bearing portion 112, upstream bearing portion 113) (see FIGS. 5 and 6). The lower end portion of the arm portion 114 (connecting portion with the engaged portion 115) is configured to be positioned on the substantially opposite side of the downstream bearing portion 112 (pinch roller 102) with respect to the shaft portion 116.

The guide portions 117 are guide ribs provided on the rear side of the upstream bearing portion 113, and four guide portions 117 are arranged at intervals in the left-right direction for each discharge roller unit 100. The guide portion 117 is a part of the conveyance path 51 that guides the paper S between the driving roller 101 and the pinch rollers 102 and 103 together with the plurality of guide ribs 160 (see FIGS. 2, 5, and 6) of the main body housing 2. Parts.

  As shown in FIGS. 3 to 6, the coil spring 130 is disposed between the holding member 110 and the main body frame 140 provided inside the main body housing 2, and biases the holding member 110 toward the driving roller 101. ing.

  As shown in FIGS. 3 and 4, the switching member 120 includes an operation mode of the discharge roller unit 100 in a double mode in which the two pinch rollers 102 and 103 are both pressed against the drive roller 101, and only the pinch roller 102 is a drive roller. It is a member for switching between the single mode pressed against 101.

  The switching member 120 is a long member extending in the left-right direction, and a pressing operation portion 125 is provided at a substantially central portion thereof. The pressing operation unit 125 has a shape in which a single mode switching tab 125A and a double mode switching tab 125B each formed in a rectangular plate shape are connected so as to form an obtuse angle.

  A hook portion 123 having a C-shaped cross-sectional view is provided at each of the left and right ends of the switching member 120 and the portions adjacent to the left and right sides of the pressing operation portion 125. The hook portion 123 is rotatably fitted in a pin portion 140A (see FIG. 5) fixed to the main body frame 140. The rotation center of the switching member 120 substantially coincides with the connecting portion of the single mode switching tab 125A and the double mode switching tab 125B of the pressing operation unit 125. Therefore, the switching member 120 can be rotated by pushing the single mode switching tab 125A from the upper side to the lower side or the double mode switching tab 125B from the rear side to the front side.

  The part of the switching member 120 corresponding to the position where the engaged portion 115 of the holding member 110 is disposed acts on the engaged portion 115 of the holding member 110 to realize rotation and positioning of the holding member 110. An abutting action part 122 as an example of the abutting part is formed.

  The pressing operation portion 125, the hook portion 123, and the abutting action portion 122 of the switching member 120 are connected by a connecting portion 121, and in conjunction with the pressing operation of the pressing operation portion 125, four abutting action portions 122 ( 3 and 4 rotate only around the pin portion 140A. Note that most of the long main body of the switching member 120 (such as the connecting portion 121 and the abutting action portion 122) is isolated from the transport path 51 by the cover portion 150, as shown in FIG.

  As shown in FIGS. 5 and 6, the abutting action portion 122 of the switching member 120 pushes down the single mode switching tab 125 </ b> A of the pressing operation portion 125, thereby engaging the lower end portion of the arm portion 114 of the holding member 110. The arm portion 114 is rotated by coming into contact with the portion 115 from the rear, so that the entire holding member 110 is pushed down against the urging force of the coil spring 130 and the ridge of the upper surface 115S of the engaged portion 115 is overcome and engaged. It is configured.

  In addition, the regulating surface 140S of the main body frame 140 is disposed at a position facing the front lower end portion (corner portion 114S) of the arm portion 114 of the holding member 110 in a state where the contact action portion 122 of the switching member 120 is engaged. ing. The restricting surface 140S is formed of a part of a flat wall of the main body frame 140, and the arm portion 114 that is rotated by depressing the single mode switching tab 125A of the pressing operation portion 125 exceeds the engaged state shown in FIG. It plays a role to prevent it from turning too much.

  In the single mode, the contact member 122 that engages with the lower end of the rear surface of the arm portion 114 of the holding member 110 and the regulation surface 140S of the main body frame 140 that is disposed to face the lower end of the front surface of the arm portion 114 are in the single mode. The “regulating means” is configured to lock the position of 110 in the front-rear direction (paper discharge direction).

The guide ribs 160 shown in FIGS. 2, 5, and 6 are plate-like members that are vertically arranged from the surface of the cover unit 150 and are arranged along the sheet conveyance direction, and are directed from the conveyance roller 52 toward the discharge roller unit 100. A guide surface inside the transport path 51 is defined. Pushing operation section 125 of the switching member 120 disposed on the outer side of the cover 150, between the guide ribs 160 are disposed at positions which do not project to the conveying path 51 side of the sheet S from the guide rib 160.

<Operation mode switching operation>
By configuring the discharge roller unit 100 and its peripheral structure in the transport unit 5 as described above, the operation mode of the discharge roller unit 100 is pressed against the drive roller 101 together with the two pinch rollers 102 and 103. It is possible to switch between the double mode and the single mode in which only one of the two pinch rollers (downstream pinch roller 102) is pressed against the driving roller 101. Hereinafter, the operation mode switching operation will be described in detail with reference mainly to FIGS. 5 and 6.

  When operating in the double mode, as shown in FIG. 5, the two pinch rollers 102 and 103 are held substantially horizontally. The drive roller 101 is disposed above a position where the rotation shaft is substantially equidistant from the rotation shafts of the pinch rollers 102 and 103. The holding member 110 that holds the two pinch rollers 102 and 103 is urged upward by the coil spring 130, so that the pinch rollers 102 and 103 are pressed against the driving roller 101.

  When operating in such a double mode, the pinch rollers 102 and 103 are pressed against the drive roller 101 at two locations in the paper discharge direction. That is, the driving roller 101 enters between the pinch rollers 102 and 103 and is sandwiched from the front and rear, and the upward biasing force by the coil spring 130 always acts as a balanced force in the front and rear direction along the paper discharge direction. Will do. Therefore, when the sheet S is discharged, the positions of the pinch rollers 102 and 103 are stably held without being shifted back and forth.

  At this time, the contact action portion 122 of the switching member 120 is in the position shown in FIG. 5 and is not engaged with the engaged portion 115 at the tip of the arm portion 114 extending from the holding member 110. The position of the switching member 120 that realizes the operation in the double mode is referred to as a “double mode position”.

  In this state, when the single mode switching tab 125A of the pressing operation portion 125 of the switching member 120 is pressed down, the contact action portion 122 is the upper surface 115S of the engaged portion 115 provided at the tip of the arm portion 114 of the holding member 110. While being in sliding contact with the pin portion 140A, the pin portion 140A is rotated forward. Then, the holding member 110 rotates while displacing the shaft portion 116 downward along the groove portion 145G of the support portion 145 against the urging force of the coil spring 130, and the posture (first position) shown in FIG. And single mode is realized.

  The position of the switching member 120 that realizes the operation in the single mode shown in FIG. 6 is referred to as a “single mode position”. In the single mode position, the contact action portion 122 of the switching member 120 is above (slightly obliquely rearward) the engaged portion 115 formed at the lower end portion of the arm portion 114 biased upward by the coil spring 130. Is engaged from.

  At the time of operation in the single mode, as shown in FIG. 6, the upper part of the holding member 110 (the side on which the downstream bearing portion 112 and the upstream bearing portion 113 are provided) is inclined backward, and the shaft portion 116 is displaced downward. Thus, only the pinch roller 102 is positioned so as to be pressed against the driving roller 101. At this time, unlike the operation in the double mode, the biasing force of the spring does not act so as to prevent the pinch roller 102 from swinging back and forth, so that the position of the pinch roller 102 is shifted back and forth when the paper S is discharged. The position of the holding member 110 (holder part) in the paper discharge direction is locked by the “regulating means” so as not to be present.

  The restricting means rotates the holding member 110 on the lower end side of the arm portion 114 that extends to the opposite side of the “holder portion” (the bearing portions 112 and 113 side) with respect to the shaft portion 116 that is the rotation center of the holding member 110. Acts to regulate movement. Specifically, when the restricting unit acts as follows, the rotation of the holding member 110 during the operation in the single mode is restricted.

(1) The contact action portion 122 of the switching member 120 gets over the bulge of the upper surface 115S of the engaged portion 115, engages with a corner portion connected to the engaged portion 115 at the lower end of the rear surface of the arm portion 114, and the coil It is locked by the action of the spring 130. At this time, the abutting action part 122 is engaged with the engaged part 115 of the arm part 114 from slightly upward and slightly rearward, and the arm part 114 is prevented from returning backward.

(2) When the holding member 110 is in the posture (first position) shown in FIG. 6, the chamfered corner portion 114 </ b> S formed at the lower front end portion of the arm portion 114 faces the restriction surface 140 </ b> S of the main body frame 140. Therefore, the holding member 110 does not rotate more than necessary. In addition, the position of the corner portion 114S at this time may be a position that accurately contacts the restriction surface 140S, but there may be some gap between the restriction surface 140S.

  Thus, the rearward rotation of the arm portion 114 (displacement of the pinch roller 102 forward) is blocked by the abutting action portion 122 of the switching member 120, and the forward rotation of the arm portion 114 (pinch roller). The rearward displacement of the main body 102 is regulated by the regulation surface 140S of the main body frame 140 disposed inside the main body housing 2.

  When returning the operation mode of the discharge roller unit 100 from the single mode to the double mode, the double mode switching tab 125B of the pressing operation unit 125 is pushed forward. Then, the abutting action part 122 rotates backward about the pin part 140 </ b> A while slidingly contacting the upper surface 115 </ b> S of the engaged part 115 provided at the tip of the arm part 114 of the holding member 110. At that time, the holding member 110 rotates while displacing the shaft portion 116 along the groove portion 145G of the support portion 145 against the urging force of the coil spring 130, and the posture shown in FIG. Return to posture (second position).

<Effect of color printer>
According to the color printer 1 of the present embodiment configured as described above, the following effects can be obtained.

  Regardless of whether the operation mode of the discharge roller unit 100 that can be switched in accordance with the change of the type of the sheet S is “single mode” or “double mode”, the position of the holding member 110 swings in the sheet discharge direction. Stabilize without.

  In general, it is expected that the forward curled state of the paper after fixing is removed by the pressure contact of the discharge roller. However, if the position of the holding member 110 is unstable, the forward curled state cannot be completely removed or the forward curled state may be removed. Instead of being removed, it will be discharged in a cylindrical curl state, and the desired curl removal performance will not be exhibited.

  In the present embodiment, since the position of the holding member 110 is stabilized, desired curl removal performance is exhibited in each of the operation modes of “single mode” and “double mode”. Ordered stacking of the sheets S after being discharged and discharged becomes possible.

  The action of the switching member 120 for rotating the holding member 110 between the “first position” and the “second position” is downstream of the shaft portion 116 that is the rotation center of the holding member 110. Since it is configured to receive the engaged portion 115 provided at the distal end of the arm portion 114 located on the opposite side of the bearing portion 112, it is necessary for the switching operation of the pressing operation portion 125 by appropriately setting the arm length and the like. The angle and strength of the pressing force can be optimized. Therefore, it is possible to design the switching member 120 with good operability that allows a smooth switching operation.

  Further, the upper surface 115S of the engaged portion 115 provided at the tip of the arm portion 114 of the holding member 110 is formed in a shape in which the substantially central portion in the front-rear direction is raised so that the contact acting portion 122 of the switching member 120 is brought into sliding contact. Thus, the operation mode can be switched smoothly while pushing down the holding member 110 using the elasticity of the coil spring 130.

  In the “single mode”, the restricting means for locking the position of the holding member 110 in the sheet discharge direction is restricted on the opposite side of the pinch roller 102 with respect to the shaft portion 116 that is the rotation center of the holding member 110. It is possible to easily restrict the pinch roller 102 from shifting backward (too much rotation) when switching to the mode. In the present embodiment, this is realized by using a part of the main body frame 140 inside the cover unit 150 that does not interfere with the conveyance of the paper in the conveyance path 51.

  In the “single mode”, a part of the switching member 120 (abutment action part 122) and a part of the main body frame 140 (a regulation surface 140S) are used as the regulation means for locking the position of the holding member 110 in the paper discharge direction. Therefore, it is not necessary to add a separate part as a regulating means, and a simple configuration that contributes to downsizing of the apparatus and reduction of manufacturing costs is realized.

  Since the pressing operation portion 125 provided on the switching member 120 for switching the operation modes of the plurality of discharge roller units 100 at the same time is disposed in the range where the discharge roller unit 100 is provided, the drive roller of the discharge roller unit 100, for example, Compared with the case where the pressing operation unit 125 is provided on the outer side in the axial direction of 101, interference with other members does not become a design restriction, leading to a reduction in the size of the entire apparatus.

  Further, since the pressing operation unit 125 is provided in the center of the range in which the discharge roller unit 100 is provided in the axial direction of the driving roller 101, the pressing force required for the switching operation of the pressing operation unit 125 is relatively small. I'll do it. Therefore, the switching operation can be performed more smoothly. In addition, there is an advantage that design restrictions considering the torsional rigidity of the switching member 120 are reduced, and it is easy to realize weight reduction and downsizing of parts and the entire apparatus.

A plurality of guide ribs 160 constituting the conveyance path 51 are provided between the image forming unit 4 and the discharge roller unit 100, and are configured to guide the conveyance of the paper S from the image forming unit 4 to the discharge roller unit 100. Since the member 120 (particularly, the pressing operation portion 125) is arranged at a position where it does not protrude from the guide rib 160 toward the conveyance path 51, an arrangement that facilitates the switching operation without hindering the conveyance of the paper S is realized. Yes.

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

  In the embodiment, the restricting means includes a contact portion (contact operation portion 122) provided in the switching member 120, and a part of the main body frame 140 (restricting surface 140 </ b> S) disposed inside the main body housing 2. However, the present invention is not limited to the specific configuration exemplified in the embodiment.

  For example, the switching member 120 may act on the holding member 100 alone to lock the position in the paper discharge direction, or may be indirectly locked via other components. Further, a structure corresponding to the regulation surface 140S may be arranged by other parts provided on the main body frame 140 instead of a part of the main body frame 140.

  In the said embodiment, although the form which has arrange | positioned the discharge roller unit 100 at intervals 4 was illustrated, this invention is not limited to such a specific structure. For example, the number of discharge roller units 100 is appropriately determined according to the size and structure of the image forming apparatus to be applied, and may be one in some cases. However, if the number is two or more, as described above, the pressing operation unit can be arranged in the range where the discharge roller unit is provided. If the number is an even number, the discharge roller units are arranged at almost equal intervals. It is advantageous in that it can be arranged at the center.

  In the above-described embodiment, an example in which a plurality of guide ribs is employed as a member constituting the paper conveyance path 51 is exemplified. However, the conveyance path of the recording sheet to which the present invention is applicable is not limited thereto. For example, the conveyance path may be defined by a wall having a guide surface. In this case, if the pressing operation portion of the switching member is exposed (not projected) from the opening formed in the guide surface and can be operated, an arrangement that does not hinder the conveyance of the paper S can be realized.

  The configuration of the image forming unit 4 shown in the above embodiment is an example, and can be changed as appropriate. For example, instead of the exposure device 41 that exposes the photosensitive drum 42A with laser light, an exposure device that exposes the photosensitive drum 42A with light emitted from an LED element, EL element, phosphor, or the like may be employed. Further, instead of the fixing device 44 including the heating roller 44A and the pressure roller 44B, a film fixing type fixing device may be employed.

  In the embodiment, the color printer 1 is exemplified as the image forming apparatus. However, the image forming apparatus is not limited thereto, and may be a monochrome printer, for example. The image forming apparatus is not limited to a printer, and may be, for example, a copying machine or a multifunction machine.

  In the embodiment, the paper S such as so-called plain paper or postcard is shown as an example of the recording sheet. However, the recording sheet is not limited to this, and may be an OHP sheet, for example.

1 Color printer (image forming device)
2 Main Body Case 4 Image Forming Unit 100 Discharge Roller Unit 101 Drive Roller 102 Pinch Roller 103 Pinch Roller 110 Holding Member 114 Arm Part 120 Switching Member 122 Contacting Action Part 125 Pressing Operation Part 130 Coil Spring (Biasing Member)
140 Body frame 140S Restricting surface S Paper

Claims (5)

A housing,
An image forming unit provided inside the housing and forming an image on a recording sheet;
A recording roller having a driving roller, two pinch rollers arranged side by side in the sheet discharge direction at a position facing the driving roller, and a holding member that holds the two pinch rollers, and conveyed from the image forming unit A discharge roller unit for discharging the sheet to the outside of the housing;
A biasing member that biases the holding member toward the drive roller;
The operation mode of the discharge roller unit is between a double mode in which the two pinch rollers are pressed against the drive roller and a single mode in which only one of the two pinch rollers is pressed into the drive roller. A switching member to be switched with,
A regulating means for locking the sheet discharge direction position of the holding member in the single mode ,
The holding member is rotatably supported around an axis parallel to the drive roller, and is displaceable between a first position that realizes the single mode and a second position that realizes the double mode,
The switching member is rotatably supported around an axis parallel to the driving roller, and is displaceable between a single mode position for realizing the single mode and a double mode position for realizing the double mode. The holding member rotates in conjunction with the rotation of the member, and when the switching member is switched to the single mode position, the holding member is switched to the first position, and the switching member is switched to the double mode position. A holding member is configured to be disposed in the second position;
The restricting means includes a contact portion provided on the switching member and a part of a main body frame disposed inside the housing, and the contact portion of the switching member in the single mode position. However, the image forming apparatus is characterized in that rotation of the holding member is restricted against the urging force of the urging member, and a part of the main body frame restricts rotation of the holding member . The holding member includes a holder portion that holds the two pinch rollers, and an arm portion that extends to the opposite side of the holder portion with respect to the rotation center of the holding member,
In the single mode position, the abutting portion of the switching member abuts on the arm portion to restrict rotation in one direction of the holder portion, and a part of the main body frame abuts on the arm portion. The image forming apparatus according to claim 1 , wherein the rotation of the holder portion in the other direction is restricted. A plurality of the discharge roller units are provided,
The switching member includes a pressing operation unit for simultaneously switching operation modes of the plurality of discharge roller units,
The pressing operation portion, an image forming apparatus according to claim 1 or claim 2, wherein the plurality of discharge roller unit in the axial direction of the drive roller is provided within the range provided. The image forming apparatus according to claim 3 , wherein the pressing operation unit is provided at a center of a range in which the plurality of discharge roller units are provided in an axial direction of the driving roller. A plurality of guide ribs for guiding the conveyance of the recording sheet from the image forming unit to the discharge roller unit are provided between the image forming unit and the discharge roller unit.
The switching member, the image forming apparatus according to any one of claims 1 to 4, characterized in that it is arranged at a position not projecting conveying path of the recording sheet from the guide ribs between said plurality of guide ribs .

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