JP2005148365A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a simple mechanism which is used to match a charging start position, where a suction belt of a carrier device is charged, with a position where a paper being carried from a both surface unit to print a second surface contacts with the carrier device. <P>SOLUTION: Paper which has been carried through a first path A and printed on a first surface is transmitted into a second path B of the both surface unit 6 by a carrier device 1 whose driving direction has been switched over. When the paper's front and back are reversed by the both surface unit 6 and the paper arrives at the location of a paper sensor 10, the paper sensor 10 is turned ON, the carrier device 1 is stopped and the paper is stopped. Then, the driving direction of the carrier device 1 is again switched over and a charger 5 charges a suction belt 4. When first and second carrier rollers 21 and 22 of the both surface unit 6 are driven with the timing in which the charging start position of the surface belt 4 reaches the location of the paper sensor 10, the paper is sucked onto the suction belt 4, carried under a recording head 11 and printing is conducted on the second surface. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus capable of double-sided printing. More specifically, the present invention uses a conveyance device that adsorbs a sheet from a duplex unit that inverts a sheet for printing on a second side to the printing unit by adsorbing the sheet with an electric charge. The present invention relates to an image forming apparatus.

  2. Description of the Related Art Conventionally, an image forming apparatus having functions such as a printer, a copying machine, and a facsimile is configured to form an image on a recording medium such as paper or a plastic thin plate based on image information. In the image forming apparatus, the paper is fed to the recording position in the paper feeding unit, and the recording unit (recording head) is driven in the recording unit to perform printing on the paper. In such an image forming apparatus, only one side of the paper can be recorded. When recording on both sides, after the recording on one side is finished, the discharged paper is turned upside down. Paper was fed again and double-sided printing was performed.

Many conventional techniques are known for an image forming apparatus that realizes double-sided printing on paper.
In the image forming apparatus described in Patent Document 1, the sheet on which the image is fixed on the surface in the main conveyance path is guided to the sheet discharge tray side by the normal rotation of the sheet discharge roller capable of normal / reverse rotation. The paper is temporarily stopped with the trailing edge of the paper sandwiched between the paper discharge rollers, and then the paper discharge roller is rotated in the reverse direction, the paper is guided to the sub-transport path, the paper is turned upside down, front and back, and the main transport again. After returning to the path and passing through the sub-transport path and returning to the main transport path, an image is formed and fixed on the back surface of the sheet by the photosensitive member.

In the ink jet recording apparatus described in Patent Document 2, when printing is performed on both sides of a sheet conveyed by an adsorption belt at a position of a carriage provided with a writing unit, the trailing edge of the sheet printed on the surface is conveyed by the writing unit. After transporting to the position where it exits from the nip between the roller and the leading roller, reversely rotate the suction belt and transport roller to transport the printed paper in the reverse direction, reverse the front and back with the reversing unit, and return to the normal rotation The paper is conveyed again to the conveyed conveyance roller and the suction belt, and printed on the back surface of the paper by the writing unit. Then, the distance from the registration sensor detection position for detecting the leading edge or the trailing edge position of the sheet to the printing starting position is made larger than the distance from the position of the transfer roller to the printing start position, and the leading edge and / or the trailing edge of the sheet By eliminating or weakening the suction force of the suction belt, the paper separation property from the paper transport suction belt is improved.
JP 2002-023576 A JP 2003-205657 A

  FIG. 1 is a side view showing a schematic configuration of a main part of the image forming apparatus targeted by the present invention. Although detailed description will be given later, a sheet that has been fed upside down by a duplex unit 6 is sent. After the paper sensor 10 is turned on, the driving direction of the suction belt 4 is reversed to drive clockwise, and charging of the suction belt 4 by the charging device 5 is started. At that time, from the charging device 5 to the paper sensor 10. Is not charged. For this reason, the sheet sent from the duplex unit 6 is floated without being attracted to the suction belt 4 of the transport device 1, and the recording head 11 and the sheet may come into contact with each other to contaminate the sheet. Further, if the recording head 11 rubs against the print surface, the image may be rubbed, or the paper may hit the carriage on which the recording head 11 is mounted, causing a conveyance jam.

  Thus, due to the configuration of the recording apparatus main body, the charging start position for charging the suction belt 4 of the transport apparatus 1 and the paper transported from the duplex unit 6 for printing the second surface come into contact with the suction belt 4. When the charging device 5 is arranged at a position where the position cannot be matched, the charge is charged on the suction belt 4 until the charging start position of the suction belt 4 comes to the position of the leading end portion of the sheet. Therefore, the sheet is not attracted to the suction belt 4.

Therefore, the present invention adjusts the sheet conveyance timing in accordance with the positional relationship between the charging device and the duplex unit, so that the charging start position for charging the conveyance device and the duplex unit for printing the second surface are printed. It is an object of the present invention to provide an image forming apparatus capable of matching the position of the conveyed paper with the conveying device.
Also, it is possible to provide a mechanism having a simple configuration in which a charging start position for charging a transport device and a position where a sheet transported from a duplex unit comes into contact with the transport device for printing the second surface are matched. Objective.

  The present invention has been made to solve the above problems, and the invention according to claim 1 is directed to a duplex unit that inverts the paper to print the second surface of the paper on which the first surface is printed, and a charge. A conveying device that sucks and conveys the sheet by the charging device, and a charging device that charges the conveying device with a charge. The sheet is conveyed from the duplex unit according to the arrangement of the charging device with respect to the duplex unit. The image forming apparatus is characterized in that the conveyance timing is adjusted.

  According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the adjustment of the conveyance timing of the sheet conveyed from the duplex unit is performed by driving the conveyance roller in the duplex unit by driving the conveyance device. This is performed by delaying.

  According to a third aspect of the present invention, in the image forming apparatus according to the second aspect, the mechanism for delaying the driving of the conveying roller in the duplex unit includes an input side gear divided in the axial direction and a gear for driving the conveying roller. An output side gear is formed, and the output side gear is driven after the input side gear rotates by a predetermined angle.

The present invention includes a duplex unit that inverts the paper to print the second surface of the paper on which the first surface is printed, a transport device that adsorbs and transports the paper by charge, and charges the transport device. A charging start position for charging the transport device with a charge by adjusting a transport timing of the paper transported from the duplex unit in accordance with the arrangement of the charging device with respect to the duplex unit. In addition, it is possible to provide an image forming apparatus capable of reliably transporting a sheet by matching the position where the sheet conveyed from the duplex unit contacts the conveying device in order to print the second surface.
Further, it is possible to provide a mechanism having a simple configuration in which the charging start position for charging the transport device with the position where the paper transported from the duplex unit contacts the transport device for printing the second surface is matched. it can.

  In the image forming apparatus capable of double-sided printing, the charging start position for charging the charge of the transport device using electrostatic adsorption and the paper sent from the duplex unit for printing the second surface are transported. The position in contact with the apparatus can be adjusted by a mechanism with a simple configuration, and a double-sided unit that reverses the paper to print the second surface of the paper on which the first surface is printed, A conveyance device that adsorbs and conveys the paper, and a charging device that charges the conveyance device with charge, and the conveyance timing of the paper conveyed from the double-sided unit according to the arrangement of the charging device with respect to the double-sided unit It is an image forming apparatus that adjusts image quality.

Hereinafter, an image forming apparatus according to an embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a side view illustrating a schematic configuration of a main part of the image forming apparatus according to the embodiment.
When printing on the first side of the paper in the case of automatically performing double-sided printing for printing on the first side (front side) and the second side (back side) of the paper using the image forming apparatus of the embodiment, The paper taken out from a paper tray (not shown) is transported along the first path A by the transport device 1 and printed by the recording head 11 of the image forming unit. Here, the conveying device 1 includes an adsorption belt 4 stretched between the driving roller 2 and the driven roller 3, and the adsorption belt 4 is in a state of being charged by the charging device 5. And the recording head 11 is driven based on the image information, and printing is performed on the first surface to form a predetermined image. As a recording method of this image forming apparatus, all kinds of methods such as an ink jet method, a wire dot method, a thermal method, and a laser beam method can be adopted.

  The paper on which the first surface has been printed waits for the ink to dry with the front end protruding forward from the position of the recording head 11, and then switches the driving direction of the transport device 1 to switch back the paper. , The position of the switching plate 9 is switched, and the sheet is guided in the direction of the duplex unit 6 and fed into the second path B. In the second path B, the paper is reversed so that the printed first surface becomes the lower surface while traveling between the first and second transport rollers 7a and 8a and the first and second pressure rollers 7b and 8b. After this, the position of the paper sensor 10 provided immediately before the meeting point with the first path A is reached.

When the sheet with the first and second surfaces reversed reaches the sheet sensor 10, the sheet sensor 10 is turned on, the driving of the transport device 1 is stopped, and the sheet is also stopped at that position.
Thereafter, the driving direction of the conveying device 1 is switched again, and at the same time, charging of the suction belt 4 is started by the charging device 5. At that time, the suction belt 4 located between the charging device 5 and the paper sensor 10 is charged. Therefore, the sheet is not attracted and transported by the transport device 1.

  Next, at the timing when the portion of the suction belt 4 charged by the charging device 5 comes to the position of the paper sensor 10, the first and second transport rollers 7a and 8a in the duplex unit 6 are driven, and the paper is sucked. Adsorbed to the belt 4 and conveyed. In other words, the timing at which the first and second transport rollers 7a and 8a are driven is that the sheet on which the charged portion of the suction belt 4 is transported from the reversing unit from the time when the suction belt 4 is charged is the suction belt 4. It is delayed by the time to reach the touched position. When the sheet adsorbed by the adsorbing belt 4 reaches below the recording head 11, the recording head 11 is driven based on the image information at that position, and a predetermined image is formed on the second surface of the sheet. To be discharged.

FIG. 2 is a schematic configuration diagram showing a driving system of the conveyance roller in the duplex unit, and shows a case where the sheet is being conveyed on the first path.
The second swing gear 25 meshes with the second transport roller drive gear 22 when the sheet is transported through the first path A and when printing is performed by the recording head 11 of the image forming unit. The first and second transport roller drive gears 21 and 22 are connected to the first and second transport rollers 7a and 8a in the duplex unit 6, respectively, and the drive from the recording apparatus main body is transmitted as shown in FIG. As the drive gear 23 rotates clockwise, the second swing gear 25, the third intermediate gear 32, the second transport roller drive gear 22, the second intermediate gear 31, and the first transport meshing with the drive gear 23 are engaged. The roller drive gear 21 and other gears are driven.

FIG. 3 is a schematic configuration diagram showing a driving system of the conveying roller in the duplex unit, and shows a case where the sheet is being conveyed on the second path.
When the sheet is transported along the second path B, the first swing gear 24 meshes with the first intermediate gear 30, and the first and second transport roller drive gears 21 and 22 in the duplex unit 6 are shown in FIG. As shown, when the drive gear 23 to which the drive from the recording apparatus main body is transmitted rotates counterclockwise, the first swing gear 24, the first intermediate gear 30, and the second intermediate gear 31 are connected to the first gear 31. The second transport roller drive gears 21 and 22 are driven. As described above, the drive source of the recording apparatus main body and the duplex unit are common.

FIG. 4 is an exploded perspective view showing the second swing gear, and FIG. 5 is a perspective view showing a state in which the drive gear and the first and second swing gears are supported by the swing arm.
The drive gear 23 and the first and second swing gears 24 and 25 are supported by the swing arm 33 by swing shafts 34 and shafts 35 and 36, respectively, and can swing about the swing shaft 34. As shown in FIG. 2, when the swing arm 32 swings clockwise, the second swing gear 25 meshes with the third intermediate gear 32. As shown in FIG. 3, when the swing arm 33 swings counterclockwise, the first swing gear 24 meshes with the first intermediate gear 30. Here, as will be described below, the second swing gear 25 is divided into an input side gear 26 and an output side gear 28 in the axial direction, and the input side gear 26 meshes with the drive gear 23.

  The input side gear 26 and the output side gear 28 that are divided into two in the axial direction are in contact with each other with their side surfaces pressed. A groove 27 is formed on the contact surface of the input side gear 26 with the output side gear 28 so as to be concentric with the shaft 36 over a predetermined angle θ, and a projection is formed on the contact surface of the output side gear 28 with the input side gear 26. 29 is formed, and the projection 29 is assembled in such a relationship as to be positioned in the groove 27, and is supported by the swing arm 33 by the shaft 36.

  In the image forming apparatus shown in FIG. 1, when double-sided printing is automatically performed, the paper protruding from the front of the recording head 11 after printing on the first side is reversed to the suction belt 4 to print the second side. It is switched back by direction driving and conveyed to the second path B in the duplex unit 6. The duplex unit 6 at that time is driven by a drive system as shown in FIG. 3, and the second swinging gear 25 has a groove 27 provided in the input side gear 26 with a projection 29 provided in the output side gear 28 shown in FIG. Rotating in contact with one end C of the plate. Thereafter, when the paper turns on the paper sensor 10, the drive of the drive gear 23 is stopped, and then the swing arm 33 is swung clockwise, and the drive in the duplex unit 6 becomes a drive system as shown in FIG. . In this state, the second oscillating gear 25 does not transmit drive to other gears until the projection 29 of the output side gear 28 in FIG. 4 contacts the other end D of the groove 27 of the input side gear 26. Therefore, the driving of the first and second transport rollers 7a and 8a in the duplex unit 6 is stopped by the angle θ, so that the paper transport can be delayed for a predetermined time, and then the paper can be sent out toward the suction belt 4.

  For this reason, when the paper sensor 10 is turned on, the drive system of the duplex unit and the drive of the transport device 1 are stopped, and then the drive direction of the transport device is switched and re-driven, and at the same time, the charging device 5 moves to the suction belt 4. The charging of the charge begins. The driving of the first and second transport rollers 7 a and 8 a in the duplex unit 6 is delayed by the time required to move the distance from the position of the charging device 5 to the position of the sheet sensor 10, so that the leading edge of the sheet moves to the suction belt 4. Can be adsorbed. In addition, if the angle θ around the shaft 36 of the groove 27 formed in the input side gear 26 is changed, the time for stopping the driving of the first and second transport rollers 7a and 8a in the duplex unit 6 can be adjusted. Therefore, the paper conveyance delay can be adjusted, and the position of the charging device 5 can be set freely to some extent.

1 is a side view illustrating a schematic configuration of a main part of an image forming apparatus according to an embodiment of the present invention. It is a schematic block diagram which shows the drive system of the conveyance roller in a duplex unit, and shows the case where the paper is conveying the 1st path | route. It is a schematic block diagram which shows the drive system of the conveyance roller in a duplex unit, and shows the case where the paper is conveying the 2nd path | route. It is a perspective view which decomposes | disassembles and shows a 2nd rocking | fluctuation gear. It is a perspective view which shows a mode that a drive gear and the 1st, 2nd rocking gear are supported by the rocking | fluctuating arm.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Conveyance device, 2 ... Drive roller, 3 ... Driven roller, 4 ... Adsorption belt, 5 ... Charging device, 6 ... Duplex unit, 7a, 8a ... 1st, 2nd conveyance roller, 7b, 8b ... 1st, 1st 2 pressure roller 9 ... switching plate, 10 ... paper sensor, 11 ... recording head, 21,22 ... first and second transport roller drive gear, 23 ... drive gear, 24 ... first swing gear, 25 ... second Oscillating gear, 26 ... input side gear, 27 ... groove, 28 ... output side gear, 29 ... projection, 30, 31, 32 ... first, second and third intermediate gears, 33 ... oscillating arm, 34 ... oscillating arm Dynamic axis, 35, 36 ... axis, A ... first path, B ... second path.

Claims (3)

  A duplex unit that inverts the sheet to print the second surface of the sheet on which the first surface is printed, a conveying device that adsorbs and conveys the sheet with electric charge, and a charging device that charges the conveying device with the electric charge And adjusting the transport timing of the sheet transported from the duplex unit in accordance with the arrangement of the charging device with respect to the duplex unit.   2. The image formation according to claim 1, wherein the adjustment of the conveyance timing of the sheet conveyed from the duplex unit is performed by delaying the drive of the conveyance roller in the duplex unit from the drive of the conveyance device. apparatus.   The mechanism for delaying the driving of the conveying roller in the duplex unit is formed by forming a gear for driving the conveying roller from an input side gear and an output side gear divided in the axial direction, and after the input side gear rotates by a predetermined angle. The image forming apparatus according to claim 2, wherein the output side gear is driven.

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