JP2012006726A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily switch a conveying path for a recording sheet on which a toner image has been formed to a paper ejecting path leading to a paper ejecting roller and a reversing path leading to a reversing roller by a switching member, and to reduce noise when switching.SOLUTION: When switching the conveying path for the recording sheet S on which the toner image has been formed to the paper ejecting path L1 leading to the paper ejecting roller 27 and the reversing path L2 leading to the reversing roller 28 by the switching member 26, in a state where the switching member is energized to a cam 30 that turns the switching member by a spring 31, rotation of the paper ejecting roller is transmitted to the cam by a first rotation transmitting mechanism 40, while rotation of the reversing roller is transmitted to the cam by a second rotation transmitting mechanism 50, and the rotation of the paper ejecting roller and the reversing roller and a rotating direction of the reversing roller are controlled by a controller 62.

Description

  The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile machine, and a multifunction machine of these. In particular, a discharge roller that discharges the recording sheet on which the toner image is formed from the discharge path, and a reverse roller that reverses the conveyance direction of the recording sheet on which the toner image is formed in the reverse path and guides it to the duplex printing path. The recording sheet transporting path on which the toner image is formed is switched by a rotating switching member so that the recording sheet is switched to a discharge path for guiding the recording sheet to the discharge roller and a reversing path for guiding the reversing roller. In the image forming apparatus, noise during switching of the recording sheet conveyance path is reduced, and switching of the conveyance path by the switching member is appropriately performed by rotating the discharge roller and the reverse roller without providing another apparatus. It is characterized in that it can be controlled.

  2. Description of the Related Art Conventionally, image forming apparatuses such as copiers, printers, facsimiles, and composite machines thereof have been used which can form a toner image not only on one side of a recording sheet but also on both sides of the recording sheet. .

  In a double-sided image forming apparatus that can form a toner image on both sides of a recording sheet as described above, generally, a recording sheet on which a toner image is formed in addition to a discharge roller that discharges the recording sheet. A reversing roller that reverses the conveying direction of the recording sheet in the reversing path and guides the recording sheet on which the toner image is formed to a duplex printing path, and a discharge path that leads the recording roller to the discharge roller by a switching member; The reversing path is guided to the reversing roller.

  Here, in order to switch the conveyance path of the recording sheet on which the toner image is formed as described above by the switching member, the switching is generally performed by rotating the switching member by a solenoid.

  However, when a toner image is formed on a recording sheet, generally, the toner image transferred to the recording sheet is heated and fixed by a fixing device. Therefore, the heat is transferred to the solenoid, and in particular, the recording sheet on which the toner image is formed is transferred to the recording sheet. When transported upward, a solenoid is disposed near the upper part of the fixing device, and the heat of the fixing device greatly increases the temperature of the solenoid and causes malfunctions. There is a problem that it is necessary to provide a device or the like, and the cost is high.

  Further, when switching is performed by rotating the switching member by a solenoid, the switching member is switched by turning the solenoid ON and OFF, and when the switching member is rotated and dropped, or the switching member is rotated. There has been a problem that vibration sound or impact sound is generated due to rattling between the shaft and the bearing.

  Conventionally, as disclosed in Patent Document 1, a lever provided on a switching member is slidably contacted with a cam member while being urged by a urging member, and the cam member is rotated by a motor. In this proposal, the switching member is rotated via the lever, and the recording sheet conveyance path on which the toner image is formed is switched by the switching member.

  However, in the one shown in Patent Document 1, it is necessary to separately provide a motor for rotating the cam member, which increases the cost, and this motor is disposed in the vicinity of the upper portion of the fixing device, and its temperature is increased. Therefore, it is necessary to provide a cooling device for cooling the motor, and there is a problem that the cost is increased.

JP 2005-247467 A

  The present invention relates to a paper discharge roller that discharges a recording sheet on which a toner image is formed from a paper discharge path, and a reverse roller that reverses the conveyance direction of the recording sheet on which the toner image is formed in the reverse path and guides the recording sheet to a duplex printing path. And a switching member that rotates and switches a recording sheet conveyance path on which a toner image is formed to a discharge path that leads the recording sheet to a discharge roller and a reverse path that leads to a reverse roller. It is an object of the present invention to solve the above problems in the image forming apparatus.

  That is, in the present invention, when switching the conveyance path of the recording sheet on which the toner image is formed by the switching member as described above, noise during switching of the recording sheet conveyance path is reduced, and the conveyance path is changed by the switching member. It is an object of the present invention to make it possible to perform switching appropriately without providing another device so that the cost can be reduced.

  In the present invention, in order to solve the above-described problems, a discharge roller that discharges the recording sheet on which the toner image is formed from the discharge path, and a conveyance path of the recording sheet on which the toner image is formed are reversed. And a reversing roller for reversing and guiding the recording sheet on which the toner image is formed, by rotating a switching member for switching the conveying path of the recording sheet on which the toner image is formed, and a discharge path for guiding the recording sheet to the discharge roller. In the image forming apparatus configured to switch to the reversing path leading to the reversing roller, a rotating member that rotates the switching member, and a biasing member that biases the switching member against the rotating member, A first rotation transmission mechanism for transmitting the rotation of the paper discharge roller to the rotation member, a second rotation transmission mechanism for transmitting the rotation of the reverse roller to the rotation member, and the paper discharge roller and the reverse roller. And a control device for controlling the rotation direction of the rotation and reverse rollers, and at least a unidirectional rotation transmission member for transmitting the rotation to the second rotation transmission mechanism in only one direction, and the first rotation transmission mechanism. And the friction force between the second rotation transmission mechanism and the rotation member are made different from each other.

  Here, in this image forming apparatus, a cam or the like can be used for the rotating member that rotates the switching member.

  Further, in this image forming apparatus, when the rotation of the paper discharge roller and the reverse roller and the rotation direction of the reverse roller are controlled by the above-described control device, the recording sheet guided to the switching member is detected in order to detect the timing. It is preferable to provide a sheet detection device.

  In this image forming apparatus, before the recording sheet on which the toner image is formed is guided to the reversing roller, the reversing roller is temporarily moved by the control device in a direction opposite to the direction in which the recording sheet is guided to the reversing roller. The switching member is rotated and the switching member is rotated, and the recording member is guided to the reversing path by the switching member. In this state, the control device causes the reversing roller to move in the direction in which the recording sheet is guided to the reversing roller. It can be rotated to guide the recording sheet into the reversal path.

  Further, the control unit rotates the paper discharge roller in a direction to discharge the recording sheet on which the toner image is formed from the paper discharge path, and rotates the switching member. The recording sheet can be guided into the paper discharge path.

  In the image forming apparatus of the present invention, the switching member that switches the conveyance path of the recording sheet on which the toner image is formed is rotated, and the discharge path that guides the recording sheet to the discharge roller and the reverse path that leads to the reverse roller In the switching, the control device controls the rotation of the discharge roller and the reverse roller and the rotation direction of the reverse roller, and transmits the rotation of the discharge roller to the rotating member, Since the rotation member is rotated by the second rotation transmission mechanism that transmits the rotation to the rotation member, and the switching member is rotated by the rotation member, the switching member and the rotation member are rotated. There is no need to provide a separate solenoid or motor.

  For this reason, in the image forming apparatus of the present invention, unlike the case where a solenoid and a motor are separately provided, there is no occurrence of malfunction or the like due to heat radiation from the fixing device. There is no need to provide a cooling device for cooling, and the cost can be reduced.

  In the image forming apparatus of the present invention, a toner image is formed by rotating the switching member by the rotating member in a state where the switching member is urged by the urging member. Since the recorded sheet is switched between a paper discharge path that leads to the paper discharge roller and a reversal path that leads to the reversing roller, when switching the recording sheet conveyance path, the switching member drops, etc. Generation of sound is suppressed, and noise during switching can be reduced.

1 is a schematic explanatory view showing an image forming apparatus according to an embodiment of the present invention. 5 is a schematic explanatory diagram illustrating a state in which a recording sheet on which a toner image is formed is guided to a paper discharge path and discharged in the image forming apparatus of the embodiment. FIG. 6 is a schematic explanatory diagram illustrating a state in which a recording sheet on which a toner image is formed is guided to a reversal path in the image forming apparatus of the embodiment. FIG. In the image forming apparatus of the embodiment, a schematic explanatory view showing a state in which the recording sheet guided to the reversing path is guided to the duplex printing path and the recording sheet on which the toner image is formed is guided to the discharging path and discharged. It is. 5 is a schematic explanatory diagram illustrating a configuration in which a switching member that switches a conveyance path of a recording sheet on which a toner image is formed to a discharge path and a reverse path is rotated in the image forming apparatus of the embodiment. FIG. FIG. 3 is a schematic perspective view showing a mechanism for rotating a cam (rotating member) for rotating the switching member in the image forming apparatus of the embodiment. FIG. 4 is a block diagram illustrating a configuration in which the switching member is rotated by controlling the rotation of the paper discharge roller and the reverse roller in the image forming apparatus of the embodiment. In the image forming apparatus of the embodiment, a time indicating an operation timing of switching the conveyance path for conveying the recording sheet on which the toner image is fixed between the reversing path and the paper discharge path by rotating the switching member. It is a chart. In the image forming apparatus of the embodiment, it is a schematic explanatory view showing a state in which the reversing roller is rotated reversely and the switching member is rotated downward by the mechanism for rotating the cam (rotating member). In the image forming apparatus of the embodiment, a schematic view showing a state in which the reversing roller is rotated forward by the mechanism for rotating the cam (rotating member) to guide the recording sheet on which the toner image is formed to the reversing path. It is explanatory drawing. In the image forming apparatus according to the embodiment, a schematic explanatory view showing a state in which the discharge roller is rotated forward by the mechanism for rotating the cam (rotating member) and the switching member is rotated upward. . In the image forming apparatus of the embodiment, the above-described mechanism for rotating the cam (rotating member) reverses the reverse roller, reverses the recording sheet guided to the reverse path, and guides it to the duplex printing path. FIG. 5 is a schematic explanatory diagram showing a state in which a recording sheet is discharged by rotating a paper discharge roller forward.

  Next, an image forming apparatus according to an embodiment of the present invention will be specifically described with reference to the accompanying drawings. Note that the image forming apparatus according to the present invention is not limited to those shown in the following embodiments, and can be implemented with appropriate modifications within a range not changing the gist thereof.

  In the image forming apparatus of this embodiment, as shown in FIG. 1, four photoconductors 10 are rotatably provided, and yellow, magenta, cyan, and black differ in correspondence with each photoconductor 10. Four developing devices 11 containing color toner are provided.

  In this image forming apparatus, each of the photosensitive members 10 is rotated, and the surface of each of the rotating photosensitive members 10 is charged by the charging device 12.

  Next, the surface of each photoconductor 10 thus charged is exposed according to the image data by the latent image forming device 13 to form an electrostatic latent image on the surface of each photoconductor 10. For each photoconductor 10 on which an electrostatic latent image is formed in this manner, toner of a predetermined color is supplied from the corresponding developing device 11 to the electrostatic latent image portion of each photoconductor 10, and development is performed. A toner image of each color is formed on the surface of each photoconductor 10.

  Then, each of the photoconductors 10 is provided by the respective primary transfer rollers 16 provided at positions facing each other via the endless intermediate transfer belt 15 that is driven across the photoconductors 10 and the rollers 14. The toner images of the respective colors formed on the surface are primarily transferred sequentially on the intermediate transfer belt 15 to form a full-color toner image on the intermediate transfer belt 15. On the other hand, toner and other residues that are not transferred to the intermediate transfer belt 15 and remain on the surface of each photoconductor 10 are removed from the surface of each photoconductor 10 by the first cleaning device 17.

  Then, the full-color toner image formed on the intermediate transfer belt 15 as described above is guided to a position facing the secondary transfer roller 18 by the intermediate transfer belt 15.

  Further, an appropriate recording sheet S is selected from each sheet feeding cassette 19 or manual tray 20 provided at the lower part of the image forming apparatus and fed by a feeding roller 21, and this recording sheet S is intermediated by a feeding roller 22. It is guided between the transfer belt 15 and the secondary transfer roller 18.

  Then, the full-color toner image formed on the intermediate transfer belt 15 is transferred to the recording sheet S guided between the intermediate transfer belt 15 and the secondary transfer roller 18 in this way by the secondary transfer roller 18. Transfer. Further, the toner or the like remaining on the surface of the intermediate transfer belt 15 without being transferred to the recording sheet S is removed from the surface of the intermediate transfer belt 15 by the second cleaning device 23.

  Then, the recording sheet S to which the full color toner image is transferred as described above is guided to the fixing device 24, and the full color toner image transferred by the fixing device 24 is fixed to the recording sheet S.

  Thereafter, the recording sheet S on which the full-color toner image is fixed as described above is conveyed by the feed roller 22 provided on the fixing device 24, and this recording sheet S is detected by the sheet detection device 25 and provided above the recording sheet S. The triangular switching member 26 is rotated.

  When the recording sheet S on which the toner image is fixed is discharged through the paper discharge path L1, as shown in FIG. 2, the switching member 26 is rotated upward and the recording member S performs the above recording. The sheet S is guided into the paper discharge path L1, and is discharged by a paper discharge roller 27 that rotates through the paper discharge path L1.

  On the other hand, when the recording sheet S on which the toner image is fixed is reversed in the reversing path L2 and guided to the double-sided printing path L3, first, as shown in FIG. The recording sheet S is guided into the reversing path L2 by the switching member 26, and is guided to the reversing roller 28 that rotates in the paper discharge direction of the recording sheet S through the reversing path L2. The recording sheet S is conveyed in the paper discharge direction until the trailing edge of the sheet S is introduced into the reversing path L2.

  Thereafter, as shown in FIG. 4, the reversing roller 28 is rotated in the direction opposite to the paper discharge direction, and the switching member 26 is rotated upward to introduce the recording that has been introduced into the reversing path L2. The sheet S is reversed and conveyed in the reverse direction from the rear end side, and the recording sheet S is guided to the duplex printing path L3 by the feed roller 22 through the switching member 26. Further, when the switching member 26 is thus rotated upward to guide the recording sheet S to the double-sided printing path L3, the recording sheet S is guided to the next recording sheet S on which the toner image is fixed, or first to the double-sided printing path L3. Then, the recording sheet S having the toner images fixed on both sides thereof is guided into the paper discharge path L1 by the switching member 26 and is discharged by the paper discharge roller 27 that rotates through the paper discharge path L1.

  In this embodiment, when the switching member 26 is rotated, as shown in FIGS. 5 and 6, a cam 30 is used as the rotating member for rotating the switching member 26. The switching member 26 is pressed against the outer periphery by a biasing member including a spring 31.

  The first rotation transmission mechanism 40 that transmits the rotation of the paper discharge roller 27 to the first friction roller 32 that rotates the cam 30 and the second rotation transmission mechanism 50 that transmits the rotation of the reverse roller 28. Each rotation is transmitted.

  Here, in the first rotation transmission mechanism 40 that transmits the rotation of the paper discharge roller 27 to the first friction roller 32, the first gear 41 that rotates and drives the paper discharge roller 27 located above the second gear 42. And a second friction roller 44, which is a unidirectional rotation transmission member that transmits rotation to the third gear 43 in only one direction. The second friction roller 44 is brought into contact with the first friction roller 32 so that the rotation of the second friction roller 44 is transmitted to the first friction roller 32.

  Further, in the second rotation transmission mechanism 50 that transmits the rotation of the reverse roller 28 to the first friction roller 32, the fifth gear 52 is meshed with the fourth gear 51 that rotationally drives the reverse roller 28 positioned above. In addition, a third friction roller 53, which is a unidirectional rotation transmission member that transmits rotation to the fifth gear 52 only in one direction, is provided, and the fourth friction roller 54 is brought into contact with the third friction roller 53. The fourth friction roller 54 is brought into contact with the first friction roller 32 to transmit the rotation of the fourth friction roller 54 to the first friction roller 32.

  In this embodiment, the frictional force between the first friction roller 32 and the fourth friction roller 54 is greater than the frictional force between the first friction roller 32 and the second friction roller 44. When the fourth friction roller 54 rotates while the rotation of the second friction roller 44 is stopped, the first friction roller 32 and the cam 30 are rotated accordingly. ing.

  In this embodiment, the rotation of the paper discharge roller 27 and the reverse roller 28 to control the rotation of the switching member 26 is provided in the image forming apparatus as shown in FIG. The CPU 60 outputs image forming conditions such as single-sided printing and double-sided printing, detection information on the recording sheet S by the sheet detecting device 25, and the like from an image forming condition output unit 61 such as an operation panel (not shown). The control device 62 provided in the CPU 60 controls the paper discharge roller drive motor 27a for rotating the paper discharge roller 27 and the reverse roller drive motor 28a for rotating the reverse roller 28, so that the paper discharge roller 27 and the reverse roller 28 are controlled. The rotation direction of the rotation and reversing roller 28 is controlled.

  Next, FIG. 8 shows an operation of rotating the switching member 26 to switch the conveyance path for conveying the recording sheet S on which the toner image is fixed between the reversing path L2 and the paper discharge path L1. This will be described based on the time chart shown.

  Here, in order to perform double-sided printing, as shown in FIG. 3, when the switching member 26 is rotated downward and the recording sheet S is guided into the reversing path L2 by the switching member 26, a registration sensor (FIG. (Not shown) is turned ON, and the reversing roller 28 is temporarily ejected by the reversing roller 28 with the paper ejection roller 27 stopped until the recording sheet S is guided to the sheet detecting device 25. Rotate (reverse) in the direction opposite to the direction. As a result, as shown in FIG. 9, the unidirectional third friction roller 53 rotates via the fourth gear 51 and the fifth gear 52 in the second rotation transmission mechanism 50, and this third friction roller 53. Is transmitted to the first friction roller 32 via the fourth friction roller 54, and the cam 30 is rotated together with the first friction roller 32, and the switching member 26 is moved along with the rotation of the cam 30. It is turned downward against the spring 31.

  Then, when the recording sheet S is guided to the sheet detection device 25 and the sheet detection device 25 is turned on, the reversing roller 28 is rotated (normally rotated) in the sheet discharge direction of the recording sheet S. In this case, as shown in FIG. 10, the unidirectional third friction roller 53 does not rotate because the rotation direction is opposite, and the switching member 26 is rotated downward by the cam 30. Maintained at. As a result, the recording sheet S that has passed through the sheet detection device 25 is guided into the reversing path L2 and guided to the reversing roller 28, and the reversing roller 28 transports the recording sheet S in the paper discharge direction.

  Next, when the trailing edge of the recording sheet S passes through the sheet detecting device 25 and the sheet detecting device 25 is turned off, the reversing roller 28 is moved until the trailing edge of the recording sheet S is guided into the reversing path L2. While continuing to rotate (forward) the recording sheet S in the paper discharge direction, the paper discharge roller 27 is temporarily rotated in the paper discharge direction. As a result, as shown in FIG. 11, the unidirectional second friction roller 44 rotates via the first gear 41, the second gear 42, and the third gear 43 in the first rotation transmission mechanism 40. The rotation of the second friction roller 44 is transmitted to the first friction roller 32, and the cam 30 rotates in the opposite direction to the above case together with the first friction roller 32. Accordingly, the switching member 26 is rotated upward by the spring 31 described above.

  Thereafter, the reversing roller 28 is rotated (reversed) in the direction opposite to the paper discharge direction of the recording sheet S to reverse the recording sheet S guided into the reversing path L2, as shown in FIG. Then, the recording sheet S is conveyed in the reverse direction from the rear end side, passed through the switching member 26, and guided to the double-sided printing path L3. The next recording sheet S to which the image has been fixed, or the recording sheet S that has been first guided to the duplex printing path L3 and to which the toner image has been fixed on both sides is guided into the sheet discharge path L1 by the switching member 26. The paper is discharged by the paper discharge roller 27 that rotates through the paper discharge path L1.

  Here, when the reverse roller 28 is rotated (reversed) in the direction opposite to the discharge direction of the recording sheet S and the discharge roller 27 is rotated in the discharge direction as described above, as shown in FIG. The unidirectional third friction roller 53 rotates via the fourth gear 51 and the fifth gear 52 in the second rotation transmission mechanism 50, and the rotation of the third friction roller 53 causes the fourth friction roller 54 to rotate. Through the first friction roller 32, and the unidirectional second friction roller 44 rotates through the first gear 41, the second gear 42, and the third gear 43 in the first rotation transmission mechanism 40. The rotation of the second friction roller 44 is transmitted to the first friction roller 32, and the transmission of the rotation to the first friction roller 32 by the fourth friction roller 54 and the second friction roller 44 is transmitted. The springs By the biasing force of 1, it comes to be maintained in a state where the switching member 26 is rotated upward.

  In the case where the recording sheet S on which only one-side printing is performed and the toner image is fixed is discharged through the discharge path L1, the reverse roller 28 is set to the discharge direction of the recording sheet S in the same manner as described above. Is rotated (reversely rotated) in the reverse direction, and the discharge roller 27 is rotated in the discharge direction so that the switching member 26 is maintained in a state of being rotated upward.

DESCRIPTION OF SYMBOLS 10 Photoconductor 11 Developing device 12 Charging device 13 Latent image forming device 14 Roller 15 Intermediate transfer belt 16 Primary transfer roller 17 First cleaning device 18 Secondary transfer roller 19 Paper feed cassette 20 Manual feed tray 21 Paper feed roller 22 Feed roller 23 First feed roller 23 2 Cleaning device 24 Fixing device 25 Sheet detection device 26 Switching member 27 Discharge roller 27a Discharge roller drive motor 28 Reverse roller 28a Reverse roller drive motor 30 Cam (rotating member)
31 Spring (biasing member)
32 First friction roller 40 First rotation transmission mechanism 41 First gear 42 Second gear 43 Third gear 44 Unidirectional second friction roller 50 Second rotation transmission mechanism 51 Fourth gear 52 Fifth gear 53 Unidirectional Third friction roller (unidirectional rotation transmission member)
54 Fourth friction roller 60 CPU
61 Image forming condition output means 62 Control device L1 Paper discharge path L2 Reverse path L3 Duplex printing path S Recording sheet

Claims (5)

  A discharge roller that discharges the recording sheet on which the toner image is formed from the discharge path; and a reverse roller that reverses the conveyance direction of the recording sheet on which the toner image is formed in the reverse path and guides it to the duplex printing path. The switching member that switches the conveyance path of the recording sheet on which the toner image is formed is rotated to switch between the discharge path that guides the recording sheet to the discharge roller and the reverse path that leads to the reverse roller. In the image forming apparatus, a rotation member that rotates the switching member, an urging member that urges the switching member against the rotation member, and rotation of the paper discharge roller are transmitted to the rotation member. A first rotation transmission mechanism, a second rotation transmission mechanism for transmitting the rotation of the reversing roller to a rotating member, and a control device for controlling the rotation of the discharge roller and the reversing roller and the rotation direction of the reversing roller. In addition, a unidirectional rotation transmission member that transmits rotation to at least the second rotation transmission mechanism in only one direction is provided, and the frictional force between the first rotation transmission mechanism and the rotation member and the second rotation are provided. An image forming apparatus, wherein a frictional force between a transmission mechanism and a rotating member is different.   The image forming apparatus according to claim 1, wherein the rotating member is a cam.   3. The image forming apparatus according to claim 1, further comprising a sheet detecting device that detects a recording sheet guided to the switching member.   4. The image forming apparatus according to claim 1, wherein the reversing roller is temporarily moved by the control device before the recording sheet on which the toner image is formed is guided to the reversing roller. Is rotated in the direction opposite to the direction leading to the reversing roller, the switching member is rotated, and the recording sheet is guided to the reversing path by the switching member, and in this state, the reversing roller is moved by the controller. An image forming apparatus, wherein the recording sheet is guided in a reversing path by rotating in a direction leading to a reversing roller.   5. The image forming apparatus according to claim 1, wherein the control unit causes the discharge roller to discharge the recording sheet on which the toner image is formed from the discharge path. An image forming apparatus characterized in that the recording member is rotated to rotate the switching member, and the recording member is guided into the paper discharge path by the switching member.

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