JP2014010323A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus able to reduce situations in which a user erroneously takes a recording sheet that has not finished image formation in double-sided printing.SOLUTION: An image forming apparatus comprises: a housing 21; an image forming section 5; a paper feed section 32 configured to feed paper P toward the image forming section 5; an ejecting section 8 configured to eject paper P, with an image formed by the image forming section 5, out of the housing 21 through an ejection port 21A formed in the housing 21; a conveyance path 100 having a first path 110 connecting the paper feed section 32 and the image forming section 5, and a third path 130 connecting the image forming section 5 and the ejecting section 8; and a re-conveyance path 200 configured to re-convey paper P, passed through the image forming section 5, to the first path 110. The housing 21 has a first opening 21C formed separately from the ejection port 21A. The re-conveyance path 200 is configured such that paper P passed though the third path 130 is exposed outside the housing 21 through the first opening 21C, then changed in direction, and conveyed to the first path 110.

Description

  The present invention relates to an image forming apparatus including a re-conveying path.

  Conventionally, as an image forming apparatus, a conveying path for conveying a recording sheet from a feeding unit to an ejection roller via an image forming unit, and a recording sheet that has passed through the image forming unit are arranged upstream of the image forming unit in the conveying path. There is known a re-conveying path for re-conveying, and configured to be able to print on both sides of a recording sheet (see, for example, Patent Document 1).

  Specifically, the discharge roller rotates in the forward direction to discharge the recording sheet conveyed through the conveyance path to a discharge toilet provided outside the case through a discharge port formed in the case, and in the reverse direction. By rotating, the recording sheet once exposed to the outside of the casing from the discharge port is switched back into the casing. The re-conveying path conveys the recording sheet switched back by the discharge roller to the upstream side of the image forming unit in the conveying path.

JP 2009-31508 A

  By the way, in the above-described technique, when carrying out double-sided printing, when the recording sheet printed on the surface is transported from the transport path to the re-transport path, the recording sheet is temporarily discharged from the discharge port to the discharge tray. There was a possibility that the user would take the recorded sheet mistakenly as the one discharged after the printing was finished.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus that can reduce a user's mistakenly taking a recording sheet on which double-sided printing is not completed.

In order to achieve the above object, an image forming apparatus according to the present invention is directed to a housing, a sheet placement portion on which a recording sheet is placed, an image forming portion that forms an image on the recording sheet, and an image forming portion. A feeding unit that feeds the recording sheet placed on the sheet placing unit, and a discharge unit that discharges the recording sheet on which an image is formed in the image forming unit to the outside of the case through a discharge port formed in the case, The transport path having an upstream path connecting the feeding section and the image forming section, a downstream path connecting the image forming section and the discharge section, and the recording sheet that has passed the image forming section is transported again to the upstream path. Re-transport means.
The casing has a first opening formed separately from the discharge port, and the re-conveying means changes the direction after exposing the recording sheet passing through the downstream path to the outside of the casing through the first opening. And is configured to be conveyed to the upstream path.

  According to the image forming apparatus configured as described above, since the first opening is provided separately from the discharge port, the recording sheet once exposed to the outside of the housing is discharged after the printing is finished in double-sided printing. It is possible to reduce the user's mistakenly picking it up.

  The first opening is preferably provided at the lower part of the housing.

  According to this, since the recording sheet can be supported by the installation surface because the first opening is provided at a position close to the installation surface of the housing, the recording sheet exposed from the first opening is drawn into the housing. It becomes easy.

  In the image forming apparatus described above, the re-conveying unit has a switchback path that connects the first opening and the upstream path, and a return path that connects the downstream path and the switchback path, and has passed through the return path. After the recording sheet is conveyed toward the first opening, the direction may be changed, and the recording sheet may be conveyed toward the upstream path through the switchback path.

  The switchback path described above preferably also serves as a manual feed path for supplying the recording sheet inserted into the second opening formed in the housing to the conveyance path.

  According to this, the housing can be reduced in size compared with the case where the manual feed path is provided separately from the switchback path.

  The second opening is preferably common to the first opening.

  According to this, compared with the case where the second opening is provided separately from the first opening, the structure can be simplified.

Then, the switchback path described above is arranged in both the forward and reverse directions arranged so as to face the recording sheet passing through the switchback path, at the junction with the return path, or at the first opening side of the junction. You may have the conveyance roller which can rotate.
In this case, the conveyance roller rotates in one direction to convey the recording sheet in the switchback path toward the first opening, and rotates in the other direction to rotate the recording sheet in the switchback path. You may be comprised so that it may convey toward an upstream path | route.

  In the image forming apparatus in which the re-conveying path has a switchback path and a return path, the sheet placement portion is provided below the first opening and extends from the inside of the housing to the outside of the first opening. It is desirable.

  According to the image forming apparatus configured as described above, the recording sheet that has come out of the first opening can be received by the sheet placement unit.

  And it is desirable that a part of the sheet placing portion extending from the inside of the housing to the outside of the first opening is constituted by a cover for opening and closing the first opening.

  According to the image forming apparatus configured as described above, the image forming apparatus can be made compact when not in use, and dust can be prevented from entering from the first opening.

  The switchback path described above is preferably connected to the feeding unit.

  According to the image forming apparatus configured as described above, it is not necessary to provide a member for feeding the recording sheet conveyed from the re-conveying path to the image forming unit separately from the feeding unit, so that the number of parts can be reduced. Can do. Further, since only the feeding unit feeds the recording sheet to the image forming unit, the control becomes simple.

The feeding unit connected with the switchback path described above has at least one rotating body, and the image forming apparatus uses one of the recording sheet and the rotating body placed on the sheet placing portion with respect to the other. It is also possible to provide a moving mechanism for approaching or separating.
In this case, it is desirable that the moving mechanism is configured to separate the one from the other when the recording sheet is conveyed to the conveying path through the re-conveying means.

  According to the image forming apparatus configured as described above, when the recording sheet is being re-conveyed, it is possible to suppress erroneous conveyance of the recording sheet placed on the sheet placing unit. .

  In addition, the rotating body described above is arranged in contact with the recording sheet placed on the sheet placing portion and rotated to feed the recording sheet, and arranged downstream of the feeding path from the feeding roller. And the separation mechanism may be configured such that one of the recording sheet placed on the sheet placing portion and the recording sheet feeding roller approaches or separates from the other. .

In the above-described image forming apparatus, the discharge unit includes a driving roller and a driven roller that rotates following the driving force of the driving roller, and sandwiches the recording sheet between the driving roller and the driven roller. You may be comprised so that the said recording sheet may be conveyed.
In this case, the driving roller and the driven roller are a discharge position for discharging the recording sheet that has passed through the image forming unit to the outside of the housing, a re-transporting position for transporting the recording sheet that has passed through the image forming unit toward the re-transporting unit, It is desirable to be able to move between the two.

  According to the image forming apparatus configured as described above, when a roller for discharging the recording sheet and a roller for conveying the recording sheet passing through the re-conveying path are shared, each of them is provided separately. Compared to space saving.

  The image forming apparatus described above also includes a discharge posture for guiding the recording sheet that has passed through the image forming unit to the discharge unit between the image forming unit and the discharge unit on the downstream path, and the recording sheet that has passed through the image forming unit. There may be provided a switching member that can be switched between a re-conveying posture guided to the re-conveying means.

  According to the image forming apparatus configured as described above, the conveyance direction of the recording sheet can be switched with a simple mechanism.

  In the image forming apparatus described above, the conveyance path may be formed in a substantially C shape.

  According to the present invention, since the first opening is provided separately from the discharge port, the recording sheet once discharged to the outside of the housing at the time of double-sided printing is mistaken for that the printing is finished, and the user takes it. Can be reduced.

1 is a diagram illustrating a schematic configuration of a laser printer according to an embodiment of the present invention. FIG. 6 is a diagram illustrating a state after the leading edge of a sheet conveyed through a reconveying path has passed a conveying roller. It is a figure which shows the state just before a conveyance roller reversely rotates. FIG. 6 is a diagram illustrating a state after a sheet conveyed through a reconveying path is conveyed to a feeding unit. It is a figure which shows schematic structure of the laser printer which concerns on a modification.

  Next, an embodiment of the present invention will be described in detail with reference to the drawings as appropriate. In the following description, first, an overall configuration of a laser printer as an example of an image forming apparatus according to an embodiment of the present invention will be described, and then a characteristic part of the present invention will be described in detail.

  In the following description, the direction will be described with reference to the user when using the laser printer. That is, in FIG. 1, the left side toward the paper surface is “front side”, the right side toward the paper surface is “rear side”, the rear side toward the paper surface is “left side”, and the front side toward the paper surface is “right side”. To do. In addition, the vertical direction toward the page is defined as the “vertical direction”.

<Schematic configuration of laser printer>
As shown in FIG. 1, the laser printer 1 includes an apparatus main body 2, a feeder unit 3 for supplying paper P as an example of a recording sheet, a scanner unit 4, and an image for forming an image on the paper P. A forming unit 5 and a discharge unit 8 are provided.

  The apparatus main body 2 includes a housing 21 and a front cover 22. The casing 21 is provided with a discharge tray 9 on the top thereof, on which the paper P discharged out of the casing 21 by the discharge unit 8 described later is placed. The housing 21 has a wall extending upward from the rear end portion of the upper surface of the discharge tray 9, and a discharge port 21 </ b> A through which the paper P discharged by the discharge portion 8 passes is formed in this wall. Yes.

  And the housing | casing 21 has the insertion port 21B for inserting the paper P in the front part, and the 1st opening 21C. The first opening 21 </ b> C is an opening formed separately from the discharge port 21 </ b> A, and is provided in the lower portion of the housing 21. The insertion port 21B is provided below the first opening 21C.

  The front cover 22 is a cover that covers the front surface of the housing 21 and is supported by the housing 21 so as to be able to rotate back and forth around the lower end. Thereby, the front cover 22 opens and closes the insertion port 21 </ b> B and the first opening 21 </ b> C of the housing 21 by rotating in the front-rear direction.

  The feeder unit 3 is positioned below the apparatus main body 2, and includes a sheet feeding tray 31 as an example of a sheet loading unit for loading the sheet P inserted into the insertion port 21 </ b> B. A feeding unit 32 that feeds the paper P toward the image forming unit 5.

  The paper feed tray 31 includes a paper placement plate 31 </ b> A disposed at the lower part of the housing 21 and the above-described front cover 22. Specifically, the paper feed tray 31 is provided below the first opening 21C and extends from the inside of the housing 21 to the outside of the first opening 21C. The sheet placing plate 31A constitutes a portion inside the casing 21 of the sheet feeding tray 31, and the front cover 22 is a portion (partly) outside the casing 21 of the sheet feeding tray 31 in a state where the front cover 22 is tilted forward. ).

  The sheet placing plate 31A extends from a position near the front side of the housing 21 to a position near the rear side, and can be turned up and down around a turning shaft provided at the front end. The paper placing plate 31A (one side) is rotated by a known mechanism and a control device (not shown) as a push-up member 31B as an example of a moving mechanism provided below the paper placing plate 31A. The end portion rotates so as to approach or separate from a paper feed roller 32A (the other side) described later. As a result, the paper placement plate 31A lifts the paper P toward a paper feed roller 32A, which will be described later, every time when the paper P is fed, and the paper P passes through the re-transport path 200, which will be described later, to the transport path 100. When transported, the paper P can be separated from the paper feed roller 32A.

  Specifically, the sheet placement plate 31A stands by in a substantially horizontal state spaced apart from the paper feed roller 32A when there is no print command. It rotates and approaches the paper feed roller 32A. Then, after the paper P is conveyed by the paper feed roller 32A, the paper placement plate 31A is separated from the paper feed roller 32A again and returns to a substantially horizontal state.

  The feeding unit 32 mainly includes a paper feed roller 32A and a separation roller 32B as an example of a rotating body, and a separation pad 32C. The paper feed roller 32A is disposed on the rear end of the paper placement plate 31A. The separation roller 32B is disposed opposite to the separation pad 32C on the downstream side in the transport direction of the paper P from the paper feed roller 32A.

  In the feeder unit 3, the front cover 22 is tilted forward to form the paper feed tray 31, and then the paper P is placed on the paper feed tray 31. In this state, the sheet placing plate 31A is in a substantially horizontal state. Then, the rear end of the paper placement plate 31A rotates, so that the paper feed roller 32A contacts the paper P placed on the paper feed tray 31. In this state, the paper feed roller 32A rotates, so that the paper P placed on the paper feed tray 31 is sent to the separation roller 32B, and the sent paper P is moved between the separation roller 32B and the separation pad 32C. The images are separated one by one and supplied to the image forming unit 5.

  The scanner unit 4 is provided between the paper feed tray 31 and the discharge tray 9 on the front side in the housing 21 and is disposed at a distance from a photosensitive drum 61 described later. The scanner unit 4 includes a laser light emitting unit, a polygon mirror, a lens, a reflecting mirror, and the like (not shown). In the scanner unit 4, the laser beam L is irradiated on the surface of the photosensitive drum 61 by high-speed scanning.

  The image forming unit 5 is disposed above the feeding unit 32 and includes a process cartridge 6 and a fixing device 7.

  The process cartridge 6 is provided behind the scanner unit 4 in the housing 21. The process cartridge 6 includes a photosensitive drum 61, a transfer roller 62 disposed adjacent to the rear side of the photosensitive drum 61, a charger (not shown), a developing roller that is not shown, a supply roller, a toner storage chamber, and the like. ing.

  In the process cartridge 6, the surface of the rotating photosensitive drum 61 is uniformly charged by a charger, and then exposed by high-speed scanning of the laser light L from the scanner unit 4. As a result, the potential of the exposed portion is lowered, and an electrostatic latent image based on the image data is formed on the surface of the photosensitive drum 61.

  Next, the toner stored in the toner storage chamber is supplied to the electrostatic latent image on the photosensitive drum 61 by the developing roller, and a toner image is formed on the surface of the photosensitive drum 61. Thereafter, the sheet P is sandwiched between the photosensitive drum 61 and the transfer roller 62, so that the toner image carried on the surface of the photosensitive drum 61 is transferred onto the sheet P.

  The fixing device 7 is disposed above the process cartridge 6 in the housing 21, and mainly includes a heating roller 71 and a pressure roller 72.

The heating roller 71 is a member that heats the paper P, and a heat source such as a halogen lamp is provided inside thereof.
The pressure roller 72 is a member that sandwiches and conveys the paper P with the heating roller 71 and is provided obliquely above the heating roller 71.

  In the fixing device 7 configured as described above, the toner image transferred onto the paper P is thermally fixed while the paper P passes between the heating roller 71 and the pressure roller 72. Note that the paper P heat-fixed by the fixing device 7 is conveyed to a discharge unit 8 disposed on the downstream side of the fixing device 7.

  The discharge unit 8 includes a driving roller 81 and a driven roller 82 that is arranged to contact the driving roller 81 and that is driven to rotate by receiving the driving force of the driving roller 81. The paper P is transported by sandwiching the paper P between them.

  The driving roller 81 and the driven roller 82 are a discharge position (a position indicated by a solid line) for discharging the paper P that has passed through the fixing device 7 to the outside of the housing 21 and a re-conveyance of the paper P that has passed through the fixing device 7 to be described later. It can move between a re-transport position (position indicated by a two-dot chain line) transported toward the path 200.

  Specifically, when the drive roller 81 and the driven roller 82 are located at the discharge position, the contact portion between the drive roller 81 and the driven roller 82 faces the discharge port 21A. Further, when the driving roller 81 and the driven roller 82 are located at the re-conveying position, the driven roller 82 swings rearward about the driving roller 81 from the discharge position, and a contact portion between the driving roller 81 and the driven roller 82. Are arranged so as to face the entrance of the re-transport route 200.

  The driving roller 81 and the driven roller 82 are positioned at the discharge position when printing is finished by a control device (not shown) provided in the housing 21 and print on the back surface (second surface) of the paper P. When this is done, it is controlled to be positioned at the re-conveying position.

  In the discharge unit 8, when the image formation is finished, the driving roller 81 and the driven roller 82 are disposed at the discharge position, and the paper P that has passed through the fixing device 7 is discharged out of the housing 21 through the discharge port 21 </ b> A. . When printing on the back surface of the paper P, the driving roller 81 and the driven roller 82 are disposed at the re-transport position, and the paper P that has passed through the fixing device 7 does not pass through the discharge port 21A and enters the re-transport path 200. Be transported.

<Detailed configuration of transport route and re-transport route>
Next, the transport path 100 provided in the housing 21 and the re-transport path 200 as an example of the re-transport means will be described in detail.

  As shown in FIG. 1, the paper P placed on the paper feed tray 31 passes through the conveyance path 100 in the order of the feeding unit 32, the photosensitive drum 61 and the transfer roller 62, the fixing unit 7, and the discharge unit 8. It is the path | route extended in the substantially C shape formed so that. Specifically, the transport path 100 is formed by a first guide member 101, a second guide member 102, and a third guide member 103, and includes a first path 110, a second path 120, and a third path 130.

  The first path 110 is an example of an upstream path that constitutes an upstream side of the photosensitive drum 61 in the transport path 100, and connects the feeding unit 32 and the image forming unit 5 (between the photosensitive drum 61 and the transfer roller 62). It is out. The first path 110 is mainly formed by a lower portion 101A of the first guide member 101 that extends substantially in the vertical direction so as to go around the rear of the process cartridge 6.

  A lower portion 101A of the first guide member 101 extends rearward from the paper feed tray 31 through the feeding portion 32, and then is located at a lower position between the photosensitive drum 61 and the transfer roller 62 upward. It extends to.

  The second path 120 is a path provided in the image forming unit 5, and is mainly formed by the upper portion 101 </ b> B of the first guide member 101.

  The upper portion 101 </ b> B of the first guide member 101 extends upward from a position between the photosensitive drum 61 and the transfer roller 62 to a lower position between the heating roller 71 and the pressure roller 72 of the fixing device 7. ing.

  The third path 130 is an example of a downstream path constituting the downstream side of the transport path 100 with respect to the fixing device 7, and connects the image forming unit 5 (fixing device 7) and the discharge unit 8. The third path 130 is mainly formed by the second guide member 102 and the third guide member 103.

  The second guide member 102 has a substantially arc-shaped guide surface that is recessed upward, and extends forward from the outlet of the fixing device 7 to the discharge portion 8. The third guide member 103 is disposed below the second guide member 102 so as to face the second guide member 102, and forms a passage for the paper P between the third guide member 102 and the second guide member 102. The third guide member 103 extends forward from the outlet of the fixing device 7 to the entrance of a return path 210 described later.

  In the re-conveying path 200, the paper P that has passed through the fixing device 7 (image forming unit 5) is exposed to the outside of the housing 21 through the first opening 21 </ b> C, then redirected, and conveyed again to the first path 110. It is configured as follows. The re-transport route 200 includes a return route 210 and a switchback route 220.

  The return path 210 is a path that connects the third path 130 and the switchback path 220. The return path 210 diverges from the downstream side of the fixing device 7 of the third path 130 (conveyance path 100) and extends obliquely forward and downward so as to pass between the photosensitive drum 61 and the scanner unit 4 and switch back. It joins the middle part of the path 220. As a result, when the paper P that has passed through the return path 210 enters the switchback path 220, the paper P is conveyed forward (to the first opening 21 </ b> C side) in the switchback path 220. .

  Specifically, the return path 210 is formed by a fourth guide member 201, a fifth guide member 202, a sixth guide member 203, and a seventh guide member 204.

  The fourth guide member 201 is a wall of the casing 21 in which the discharge port 21A is formed. The fourth guide member 201 is a path through which the laser light L emitted from the scanner unit 4 passes from the lower side to the lower side of the discharge unit 8 (hereinafter, “ It extends to a position above the optical path.

  The fifth guide member 202 is disposed behind the fourth guide member 201 so as to face the fourth guide member 201, and forms a passage for the paper P with the fourth guide member 201. The fifth guide member 202 extends obliquely downward to the front from the lower side of the discharge portion 8 to a position above the optical path.

  The sixth guide member 203 extends on the extension line of the lower end of the fourth guide member 201 and obliquely downward and forward from a position below the optical path to a conveyance roller 230 described later.

  The seventh guide member 204 is disposed behind the sixth guide member 203 so as to face the sixth guide member 203, and forms a passage for the paper P with the sixth guide member 203. The seventh guide member 204 is on the extension line of the lower end of the fifth guide member 202, and from the position below the range through which the light emitted from the scanner unit 4 passes to the front obliquely downward direction, which will be described later. It extends to the rear side. In addition, the lower end portion (the end portion on the switchback path 220 side) of the seventh guide member 204 is bent forward and obliquely upward so that the front end faces the inside of the return path 210.

  Specifically, the lower end portion of the seventh guide member 204 is inclined with respect to a tangent at a nip portion of the later-described transport roller 230, and is upstream in the transport direction of the sheet P transported through the switchback path 220 after the switchback. The paper P is formed so as to widen toward the head. Thus, the sheet P conveyed from the front side toward the rear side through the switchback path 220 can be prevented from entering the return path 210 and can be guided to the feeding unit 32.

  Further, since the return path 210 is formed as described above, the light is emitted from the scanner unit 4 between the fourth guide member 201 and the sixth guide member 203 and between the fifth guide member 202 and the seventh guide member 204. Therefore, the return path 210 does not block the light.

  The switchback path 220 is a path that connects the first opening 21 </ b> C, the return path 210, and the feeding unit 32. The switchback path 220 is located between the paper feed tray 31 and the scanner unit 4 in the up-down direction, extends from the front side of the housing 21 toward the rear along the paper feed tray 31 in the front-back direction, and passes through the first path 110. Have joined. In addition, a first opening 21C is provided at an end of the switchback path 220 opposite to the first path 110, that is, a position corresponding to the front end. Through the first opening 21C, the switchback path 220 is provided. Can be exposed to the outside of the housing 21.

  Specifically, the switchback path 220 is formed by the eighth guide member 205, the ninth guide member 206, and the tenth guide member 207.

  The eighth guide member 205 extends from the lower edge of the first opening 21 </ b> C obliquely downward to the front side of the feeding unit 32. Note that the rear end of the eighth guide member 205 is in contact with the paper P placed on the paper placement plate 31A in a state where the paper placement plate 31A is rotated upward (closer to the paper feed roller 32A). It extends to the position where it does not touch. When the conveyance of the paper P from the eighth guide member 205 to the paper feed roller 32A is unstable, a film or the like is provided at the rear end of the eighth guide member 205 to guide the paper P to the paper feed roller 32A. You may make it the structure to make.

  The ninth guide member 206 is disposed above the front portion of the eighth guide member 205 so as to face the eighth guide member 205, and forms a passage for the paper P with the eighth guide member 205. . The ninth guide member 206 extends from the upper edge of the first opening 21 </ b> C obliquely downward to the front side of the transport roller 230. As a result, the paper P transported from the front side to the rear side of the switchback path 220 can be guided to the transport roller 230.

  The tenth guide member 207 is disposed above the rear portion of the eighth guide member 205 so as to face the eighth guide member 205, and forms a passage for the paper P with the eighth guide member 205. Yes. The tenth guide member 207 extends from the rear side of the seventh guide member 204 of the return path 210 toward the front side of the feeding unit 32. More specifically, the tenth guide member 207 is inclined backward and downward so that the path of the paper P becomes narrower toward the feeding unit 32 side. As a result, the paper P can be guided to the paper feed roller 32A.

  The switchback path 220 faces the sheet P passing through the switchback path 220 on the opposite side of the first path 110 with respect to the merged part with the return path 210, that is, on the first opening 21C side. Conveying rollers 230 arranged in this manner are provided. The switchback path 220 and the conveyance roller 230 constitute a switchback means 240 that reverses the traveling direction of the paper P that has passed through the return path 210 and conveys it to the first path 110.

  The transport roller 230 is configured to be rotatable in both forward and reverse directions, and is rotated in one direction so that the paper P in the switchback path 220 moves away from the first path 110, that is, toward the first opening 21C. By conveying in the direction and rotating in the other direction, the paper P in the switchback path 220 is conveyed in the direction toward the first path 110.

  The transport roller 230 rotates in one direction while the paper P is transported through the return path 210 by the control device, and the rear end of the paper P transported through the return path 210 is switched back to the return path 210. After reaching between the paths 220 (after passing through the lower end of the seventh guide member 204), it is controlled to rotate in the other direction.

  Thereby, the switchback means 240 transports the paper P transported from the return path 210 to the switchback path 220 by the transport roller 230 so as to be exposed to the outside of the housing 21 through the first opening 21C. After the trailing edge of the paper P reaches the joining portion of the return path 210 and the switchback path 220, the direction is changed, and the paper P can be conveyed toward the feeding unit 32 with the trailing edge as the head. It can be done.

  In addition, the switchback path 220 can supply the inserted paper P to the transport path 100 (first path 110) by inserting the paper P from the first opening 21C. That is, the switchback path 220 also serves as a manual feed path, and the first opening 21C also serves as a manual feed opening (second opening). Note that when printing on the paper P by manual feeding, the transport roller 230 is controlled to rotate in the other direction by the control device.

Next, the operation of the laser printer 1 configured as described above will be described.
When performing double-sided printing, as shown in FIG. 1, first, the push-up member 31 </ b> B rises, and the paper P on the paper placement plate 31 </ b> A approaches the feeding unit 32. As a result, the paper P on the paper placement plate 31 </ b> A (the paper feed tray 31) is supplied to the image forming unit 5 through the first path 110 by the feeding unit 32. At this time, the laser light L emitted from the scanner unit 4 irradiates the surface of the photosensitive drum 61 with high-speed scanning.

  The sheet P supplied to the image forming unit 5 passes between the photosensitive drum 61 and the transfer roller 62 to form an image on the surface, and then is conveyed to the fixing device 7 through the second path 120. . Then, the paper P that has passed through the fixing device 7 is conveyed to the third path 130. At this time, as shown in FIG. 2, the discharge unit 8 moves the driving roller 81 and the driven roller 82 to the re-transport position, and the sheet P transported through the third path 130 does not pass through the discharge port 21A. Transport toward return path 210.

  The sheet P conveyed through the return path 210 passes between the scanner unit 4 and the photosensitive drum 61 and is then conveyed to the conveyance roller 230 of the switchback path 220. Note that when the leading edge of the paper P reaches between the scanner unit 4 and the photosensitive drum 61, the image formation on the surface of the paper P is finished, and the laser beam L is not irradiated.

  Then, the sheet P conveyed from the return path 210 to the switchback path 220 is directed toward the first opening 21C until the trailing edge of the sheet P passes through the return path 210 by the conveying roller 230 as shown in FIG. Are transported. At this time, the front end side of the paper P is exposed from the first opening 21 </ b> C to the outside of the housing 21, and the exposed portion is supported by the front cover 22 constituting the paper feed tray 31.

  When the trailing edge of the paper P passes through the return path 210 and enters the switchback path 220, the transport roller 230 rotates in the reverse direction. Thereby, as shown in FIG. 4, the paper P in the switchback path 220 is conveyed toward the feeding unit 32 (first path 110) with the rear end at the head. At this time, the push-up member 31B is lowered, and the paper P on the paper placement plate 31A is in a state of being separated from the feeding unit 32.

  In this way, the sheet P that has passed through the fixing device 7 and is transported on the re-transport path 200 is transported again on the transport path 100 with the front and back sides reversed, and an image is formed on the back surface. In addition, after the rear end of the paper P passes between the scanner unit 4 and the photosensitive drum 61, the laser light L is irradiated for image formation on the back surface of the paper P. Then, as shown in FIG. 1, the sheet P on which the image is formed is discharged out of the housing 21 by the driving roller 81 and the driven roller 82 of the discharging unit 8 moved to the discharging position.

According to the above, the following effects can be obtained in the present embodiment.
Since the first opening 21C for discharging the paper P once out of the housing 21 at the time of switchback is provided separately from the discharge port 21A, the first opening 21C is temporarily out of the housing 21 in order to switch back during double-sided printing. It can be reduced that the user takes the discharged paper P mistakenly after being printed and discharged.

  Since the first opening 21C is provided in the lower part of the casing 21, the lower surface of the paper P discharged from the first opening 21C is placed on the paper feed tray 31 (first opening) provided immediately below the lower surface. 21C). Even if the paper feed tray 31 does not protrude to the outside of the housing 21, if the installation surface of the housing 21 is in front of the first opening 21C, the first opening on the installation surface The lower surface of the paper P discharged from 21C can be supported. As a result, if the first opening is provided in the upper part of the housing, the sheet hangs down from the first opening, whereas in the present embodiment, the sheet P discharged from the first opening 21C is removed. Since it can be maintained in a substantially horizontal posture, it can be easily pulled into the housing 21 when switching back.

  Further, since the paper feed tray 31 extends from the inside of the housing 21 to the outside of the first opening 21C, for example, the laser printer 1 is installed on a table, and the installation surface is on the front side of the first opening 21C. Even if it is not, the paper P discharged from the first opening 21C can be reliably supported by the paper feed tray 31. As a result, the paper P discharged from the first opening 21C is maintained in a substantially horizontal posture without sagging, so that the paper P can be easily drawn into the housing 21 when the paper P is switched back.

  The portion outside the casing 21 of the paper feed tray 31 is composed of a front cover 22 that opens and closes the first opening 21C, so that it can be made compact when the laser printer 1 is not used. . Further, by closing the front cover 22, it is possible to reduce dust from entering the housing 21 from the first opening 21C.

  Since the downstream end of the re-conveying path 200 (switchback path 220) is connected to the feeding unit 32, the sheet P conveyed from the re-conveying path 200 is separated from the photosensitive unit 61 separately from the feeding unit 32. Therefore, it is not necessary to provide a member to be fed between the transfer roller 62 and the transfer roller 62 (image forming unit 5), so that the number of parts can be reduced. Further, since the only member that feeds the paper P between the photosensitive drum 61 and the transfer roller 62 is the feeding unit 32, the control for determining the timing of image formation and the like becomes simple.

  Further, the push-up member 31B moves downward so as to separate the paper placing plate 31A from the feeding unit 32 when the paper P is transported to the transport path 100 through the re-transport path 200, and therefore on the back surface. When printing is performed, it is possible to suppress the conveyance of the paper P placed on the paper placement plate 31A (paper feed tray 31) by mistake.

  The drive roller 81 and the driven roller 82 of the discharge unit 8 are configured to discharge the paper P when positioned at the discharge position and to transport the paper P to the return path 210 when positioned at the re-transport position. Since the roller for discharging the paper P and the roller for transporting the paper P passing through the re-conveying path 200 are shared, the space is saved compared to the case where each roller is provided separately.

  In addition, since the switchback path 220 also serves as a manual feed path, the housing 21 can be downsized compared to the case where the manual feed path is provided separately from the switchback path 220.

  The first opening 21C for once exposing the paper P passing through the re-conveying path 200 to the outside of the housing 21 and the opening (second opening) for inserting the paper P for manual feeding are made common. Can be simplified.

  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 addition, about the component similar to the said embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

  In the embodiment, the driving roller 81 and the driven roller 82 of the discharge unit 8 are configured to be movable between the discharge position and the re-transport position, thereby switching the transport direction of the paper P transported through the third path 130. However, the present invention is not limited to this. For example, as shown in FIG. 5, a flapper 300 as an example of a switching member is provided between the fixing device 7 and the discharge unit 8 in the third path 130 so as to be able to swing, and the third path 130 is conveyed by the flapper 300. The transport direction of the paper P to be printed may be switched.

  Specifically, the flapper 300 extends downward from the upper side of the third path 130 so as to intersect the third path 130, and discharges the paper P that has passed through the fixing device 7 with the leading end facing the discharge unit 8. The discharge posture (the posture shown by the solid line) for guiding to the section 8 and the re-transport that guides the paper P that has passed through the fixing device 7 to the return path 210 (re-transport route 200) with the leading end facing the entrance side of the re-transport route 200 It is possible to switch between postures (positions indicated by broken lines).

  The flapper 300 is controlled by the control device so as to be in a discharging posture when the image formation is finished, and in a re-conveying posture when printing on the back surface of the paper P.

  By providing such a flapper 300, the transport direction of the paper P transported through the third path 130 can be switched with a simpler mechanism than in the above embodiment.

  In the embodiment, the first opening 21C for temporarily discharging the paper P to the outside at the time of switchback is common with the manual feed opening (second opening). However, the present invention is not limited to this. is not. For example, the housing 21 has a second opening formed separately from the first opening 21 </ b> C, and the paper P is supplied to the switchback path 220 by inserting the paper P from the second opening. It may be configured to be able to.

  In the above-described embodiment, the feeding unit 32 has two rotating bodies, that is, the paper feed roller 32A and the separation roller 32B. However, the present invention is not limited to this, and the feeding unit has one rotating body. May be included, or three or more rotating bodies may be included.

  In the embodiment, as the moving mechanism, the push-up member 31B that moves the paper placement plate 31A up and down is exemplified, and the paper placement plate 31A is moved closer to or away from the feeding unit 32 by the push-up member 31B. However, the present invention is not limited to this. For example, the paper feed roller 32A is configured to be movable in the vertical direction with respect to the paper placement plate 31A. When the paper P is supplied from the paper feed tray 31 to the transport path 100, the paper feed roller 32A is fed. A moving mechanism configured to move the paper feed roller 32A away from the paper placement plate 31A when the paper roller 32A is brought close to the paper placement plate 31A and the paper P is transported from the re-transport path 200 to the transport path 100. It may be provided.

  In the above embodiment, the transport roller 230 is provided in a portion closer to the first opening 21C than the joining portion of the return path 210 and the switchback path 220. However, the present invention is not limited to this, and the transport roller 230 is transported. The roller 230 may be provided at a junction between the return path 210 and the switchback path 220.

  In the embodiment, the paper placement plate 31A is separated from the paper feed roller 32A when the paper P is conveyed to the switchback path 220 (see FIG. 4). However, the present invention is not limited to this. The paper P on the paper placement plate 31A may be separated from the paper feed roller 32A after reaching the separation roller 32B.

  In the above embodiment, the photosensitive drum 61 is configured to be exposed by the scanner unit 4, but the present invention is not limited to this. For example, an LED unit may be provided adjacent to the photosensitive drum 61 as a member for exposing the photosensitive drum 61. In this case, the return path 210 of the re-conveyance path 200 can be provided so as to pass ahead of the photosensitive drum 61 and the LED unit.

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

DESCRIPTION OF SYMBOLS 1 Laser printer 5 Image formation part 8 Ejection part 21 Case 21A Ejection port 21C 1st opening 22 Front cover 31 Paper feed tray 31B Push-up member 32 Feeding part 32A Paper feed roller 32B Separation roller 81 Drive roller 82 Follower roller 100 Conveyance path 110 First path 130 Third path 200 Re-transport path 210 Return path 220 Switchback path 230 Transport roller 240 Switchback means 300 Flapper P Paper

Claims (14)

A housing,
A sheet placement section on which the recording sheet is placed;
An image forming unit for forming an image on a recording sheet;
A feeding unit that feeds the recording sheet placed on the sheet placing unit toward the image forming unit;
A discharge unit that discharges the recording sheet on which an image is formed in the image forming unit to the outside of the case through a discharge port formed in the case;
A transport path having an upstream path connecting the feeding section and the image forming section, and a downstream path connecting the image forming section and the discharge section;
Re-conveying means for conveying the recording sheet that has passed through the image forming unit to the upstream path again,
The housing has a first opening formed separately from the discharge port,
The re-conveying means is configured to cause the recording sheet that has passed through the downstream path to be exposed to the outside of the housing through the first opening, and then redirected to be conveyed to the upstream path. An image forming apparatus.   The image forming apparatus according to claim 1, wherein the first opening is provided in a lower portion of the housing.   The re-conveying means includes a switchback path that connects the first opening and the upstream path, and a return path that connects the downstream path and the switchback path, and the recording sheet that has passed through the return path 2. The apparatus according to claim 1, wherein the recording sheet is changed in direction after being conveyed toward the first opening and conveyed toward the upstream path through the switchback path. Item 3. The image forming apparatus according to Item 2.   4. The switchback path also serves as a manual feed path for supplying a recording sheet inserted into a second opening formed in the housing to the transport path. Image forming apparatus.   The image forming apparatus according to claim 4, wherein the second opening is common to the first opening. The switchback path is arranged at the junction with the return path, or at both the forward and reverse positions arranged so as to face the recording sheet passing through the switchback path at a portion closer to the first opening than the junction. Having a rotatable transport roller,
The conveyance roller rotates in one direction to convey the recording sheet in the switchback path toward the first opening, and rotates in the other direction to rotate the recording sheet in the switchback path. The image forming apparatus according to claim 3, wherein the image forming apparatus is transported toward the upstream path.   The said sheet | seat mounting part is provided in the downward direction rather than the said 1st opening, and is extended to the outer side from the said 1st opening from the inside of the said housing | casing. The image forming apparatus described in 1.   The image forming apparatus according to claim 7, wherein a part of the sheet placement unit is configured by a cover that opens and closes the first opening.   The image forming apparatus according to claim 3, wherein the switchback path is connected to the feeding unit. The feeding unit has at least one rotating body,
A moving mechanism for moving one of the recording sheet placed on the sheet placing portion and the rotating body toward or away from the other;
The image forming apparatus according to claim 9, wherein the moving mechanism separates the one from the other when the recording sheet is conveyed to the conveyance path through the re-conveyance unit. The rotating body is disposed in contact with the recording sheet placed on the sheet placing portion to rotate and feeds the recording sheet, and is disposed downstream of the feeding path from the feeding roller. A separation roller, and
The image forming apparatus according to claim 10, wherein the moving mechanism moves one of the recording sheet and the sheet feeding roller placed on the sheet placing unit closer to or away from the other. The discharge unit includes a driving roller and a driven roller that is driven to rotate by receiving the driving force of the driving roller, and conveys the recording sheet by sandwiching the recording sheet between the driving roller and the driven roller. And
The drive roller and the driven roller are a re-conveying position that ejects the recording sheet that has passed through the image forming unit to the outside of the housing and a re-conveying unit that conveys the recording sheet that has passed through the image forming unit. The image forming apparatus according to claim 1, wherein the image forming apparatus is movable between a position and a position.   A discharge posture for guiding the recording sheet that has passed through the image forming unit to the discharge unit between the image forming unit and the discharge unit in the downstream path, and the re-conveyance of the recording sheet that has passed through the image forming unit 12. The image forming apparatus according to claim 1, further comprising a switching member that can be switched between a re-conveying posture guided to the means.   The image forming apparatus according to claim 1, wherein the conveyance path is formed in a substantially C shape.

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