JPH11258949A - Image forming device and method for controlling paper carrying guide thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent both a carrying guide and an already printed back surface from being soiled because toner does not touch the carrying guide even when the toner on the already printed back surface is melted by heat in flash fixing by accurately guiding paper by using the carrying guide at the time of automatically loading paper and separating the carrying guide from the paper at the time of printing. SOLUTION: This device is provided with a carrying guide 9 carrying the paper through a fixed gap along the opposed surface of a fixing device 7, and the guide 9 is constituted to advance and retreat. The guide 9 guides the paper only at the time of automatically loading the paper and is separated from the paper in other cases. The guide 9 is provided with the fixed gap between the fixing device 7 and the guide 9 and arranged on the downside opposed to the fixing device 7 so as to carry the paper, and guides the continuous paper 1 carried by a suction feeder 6 to a carrying roller 10 on a downstream side. At the time of automatically loading the paper, the continuously by supplied paper is guided to the carrying roller 10 on the downstream side by the guide 9. At the time of printing, the guide 9 is separated from the paper and prevented from coming in contact with the back surface of the paper so as to prevent the soiling.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, and more particularly, to a method in which a sheet is guided by a conveyance guide during automatic loading of an image forming apparatus, and during printing (fixing).
The present invention relates to an image forming apparatus and a control method of a sheet conveyance guide for separating a conveyance guide from a sheet so as to prevent a back surface of a printed sheet from being stained with toner attached to the conveyance guide.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus, in a fixing device which flashes a flash lamp to fix unfixed toner on a sheet, the fixing device moves the flash lamp in a traveling direction in order to cope with higher speed processing. A plurality of flash lamps are provided side by side, and a large number of flash lamps are flashed and fixed. Therefore, the paper path of the fixing device becomes longer in the paper transport direction as the speed of the printing apparatus increases. In order to automatically load (set) the continuous paper into the image forming apparatus having the paper path of the long fixing device, a conveyance guide is fixedly provided below the fixing device, and the continuous paper conveyed from the upstream is provided. The paper was received by the transport guide and guided to a downstream transport roller.

[0003]

However, at the time of fixing, the smoke of the unfixed toner peeled off from the paper adheres to the conveyance guide while the lamp is continuously flashed, and the adhered toner is removed by the conveyance guide. There has been a problem of soiling the back side of the paper to be guided. Further, in the case of double-sided printing, the back-printed sheet comes into contact with the conveyance guide, and the printed toner melts out due to heat at the time of fixing, and adheres to the conveyance guide by contact with the conveyance guide, There has been a problem that the attached toner stains the printed back surface of the paper guided by the transport guide.

The present invention has been made in view of the above circumstances, and a flash is used so that the printed toner on the back surface is melted by the heat at the time of fixing, and the melted toner comes into contact with the conveyance guide and does not adhere to the conveyance guide. It is an object of the present invention to provide an image forming apparatus which separates the conveyance guide from a sheet when printing is repeated, thereby preventing contact with the sheet and preventing dirt on the sheet.

[0005]

According to a first aspect of the present invention, there is provided an apparatus for fixing a toner on a sheet by fixing a toner on the sheet by flashing a flash lamp. In an image forming apparatus having a paper transport guide for transporting along a gap and having a structure in which the transport guide can move forward and backward, the transport guide guides the paper only when the paper is automatically loaded. The guide is separated from the paper.

According to a second aspect of the present invention, there is provided an apparatus having a paper transport guide on an opposite surface of a fixing device for thermally fixing toner transferred from a photoreceptor onto a paper, wherein a leading end of the continuous paper transported from a paper hopper is fixed by the fixing. A state in which the sheet is guided to a predetermined position through a gap between the container and the sheet conveyance guide, and in response to the detection signal, the conveyance guide is controlled to be retracted to a position to avoid contact with the back surface of the sheet. did.

According to the above-described method, at the time of automatic paper loading, the paper is guided to enable automatic loading, and at the time of printing, the conveyance guide is separated from the paper, and the printed back surface melted by the heat of flash fixing. To avoid contact with other toner
It is possible to prevent stains on the back surface of the paper.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a configuration diagram showing a main part of an image forming apparatus according to one embodiment of the present invention. As shown in FIG. 1, reference numeral 1 denotes a continuous sheet. Reference numeral 2 denotes a hopper on which the continuous paper 1 is placed. A photosensitive drum 3 forms a toner image on the photosensitive drum by a charging, exposure, and development process (not shown). A transfer unit 4 transfers the toner image formed on the photosensitive drum 3 to the continuous paper 1. Reference numerals 5 and 5 'denote paper transporting devices for pulling out the continuous paper 1 from the hopper 2 and transporting the continuous paper 1 to a downstream fixing device. The shape of the transport path of the sheet transport devices 5 and 5 ′ is such that the U-shape is horizontal, and the upper and lower transport paths are provided with the sheet transport devices 5 each including a tractor.
5 'is provided. Incidentally, the lower sheet conveying device 5 'may be constituted by a conveying roller. And the transfer device 4
Is disposed between the upper and lower transport devices 5, 5 '.

Reference numeral 6 denotes a suction feeder, which sucks and conveys the paper 1. Reference numeral 7 denotes a fixing device. 8 is a flash lamp. The fixing device 7 is provided with a plurality of flash lamps 8 arranged in the conveying direction of the paper 1. The fixing device 7 flashes the flash lamps 8 to melt the toner transferred to the paper by the heat of the lamp at the time of flash. Fix to 1.

Reference numeral 9 denotes a transport guide. Transport guide 9
Is provided on the lower side facing the fixing device 7 so as to convey a sheet with a certain gap between the fixing device 7 and the continuous sheet 1 conveyed by the suction feeder 6 to the downstream sheet. It is guided by a transport roller 10 as a transport unit. The transport roller 10 sandwiches the sheet with a pair of upper and lower rollers,
The paper is rotated slightly faster than the paper transport speed, and the paper is transported to the limit, and the continuous paper 1 between the paper and the suction feeder 6 is tensioned so as not to slack. Reference numeral 11 denotes a swing guide for folding the printed paper.
The swing guide 11 swings in synchronization with a perforation (folded portion) of the continuous paper to fold the paper. A sensor 12 detects the presence or absence of the continuous paper. Sensor 12
Detects that the sheet has reached the swing guide 11 when a continuous sheet is passed between the light emitting element and the light receiving element and the sheet blocks light from the light emitting element. Reference numeral 13 denotes a stacker table on which the sheet 1 folded by the swing guide 11 is placed.

Next, details of the transport guide 9 will be described with reference to FIG. FIG. 2 is a diagram illustrating details of the transport guide according to one embodiment of the present invention. As shown in FIG. 2, the fixing unit 7 indicated by a two-dot chain line shows a state where the fixing unit 7 is lifted up and opened for maintenance or the like. Reference numeral 21 denotes a paper transport guide unit provided with a plurality of the transport guides 9 arranged in the width direction of the paper. The transport guide 9 has a curved upper surface in order to reduce the frictional resistance with the paper, and the paper is brought into contact at the apex.

The transport guide 9 includes a plurality of support members 2.
Both ends are inserted into and fixed to 2 and 23 to be integrated. The support member 23 has both ends rotatably attached to a frame (not shown) by a bearing or the like. In the above-described configuration, the transport guide 9 is brought into contact with and separated from the continuous paper by moving the support member 22 up and down by means described later with the support member 23 as a fulcrum. .

Reference numeral 24 denotes an eccentric cam, and reference numeral 25 denotes an eccentric cam 2.
4 is a rotating rod for rotating the rotating member 4. The eccentric cam 24
Are supported by the rotary rod 25 through one or several pieces, and come into contact with the transport guide 9 (in FIG.
4 is in contact with the lower side of the second transport guide 9. The back side eccentric cam 24 is described to explain that a plurality of cams are provided. Therefore, this eccentric cam 24
Is not in contact with the transport guide 9, but is in contact with any one of the transport guides 9 in implementation.
The eccentric cam rotates while contacting the lower surface of the conveyance guide 9 by the rotation of, and moves the conveyance guide 9 up and down around the fulcrum 23. The rotating rod 25 is rotatably attached to a frame (not shown) similarly to the supporting member 23, and has one end (front side) extended, and the height of the paper contact surface of the transport guide 9 is adjusted to that part. A detection plate 26 for detection and a gear 27 for receiving a driving force from a driving device are attached.

Reference numeral 28 denotes a lifting / lowering motor of a driving device for moving the transport guide 9 up and down. The rotation of the lifting / lowering motor is transmitted to the gear 27 via a gear 29, and the rotary rod 25 having the eccentric cam is rotated. Move. Reference numeral 30 denotes a switch, which is a separation detection sensor that is pressed by the detection plate 26 to output a signal when the upper surface of the conveyance guide 9 is completely separated from the continuous paper 1. Reference numeral 31 denotes a switch. When the upper surface of the conveyance guide 9 is in a position where the switch comes into contact with the continuous paper 1, the contact detection sensor 26 contacts the switch and is pressed by the detection plate 26 to change the output of the switch. It is.

In the above configuration, the position of the transport guide 9 is detected by the switches 30 and 31 when the transport guide 9 comes into contact with or separated from the sheet 1, and a control device (not shown) is used based on the detected information. Then, the elevation motor 28 is rotated forward and reverse, and the transport guide 9 is moved up and down with the support member 23 as a fulcrum. FIG. 3 shows another embodiment of the transport guide described above.
As shown in FIG. 5, instead of the eccentric cam 24 and the elevating motor 28, a link fitting 32 and a solenoid 33 are used, and the solenoid 33 is turned on / off by a control device (not shown).
For example, when the solenoid 33 is energized (on) by the control device,
By pushing the middle of the link fitting 32 in the direction of the arrow with the mandrel of the solenoid 33, the middle of the link fitting 32 is bent, and the conveyance guide 9 connected to the link fitting 32 is bent.
Is pulled down around the fulcrum 23, the same effect as described above can be obtained.

As still another embodiment, instead of moving the transport guide 9 up and down in the paper transport direction as described above, as shown in FIG. 4, the transport guide 9 abutting perpendicularly to the paper surface is used. A structure in which the transport guide 9 is separated from the sheet by tilting in the horizontal direction will be described. Specifically, FIG.
As shown in (1), both ends of the transport guide 9 are extended in the paper transport direction to provide projections, and the projections are provided on the frame plate of a frame provided before and after the transport guide 9 in the paper transport direction. It is rotatably engaged with the hole 35, while
A projection is also provided at a lower portion of the conveyance guide 9 by extending a part of the guide, and the projection is engaged with a square hole provided in the connection bar 34, and is connected to one end of the connection bar 34 in the paper width direction. The solenoid 33 is connected to the solenoid 33, the solenoid 33 is energized, the connection bar 34 is pulled right in the direction of the arrow, and the conveyance guide 9 is rotated about the engagement portion 35 with the frame,
Tilt it to the left to separate the top of the transport guide 9 from the paper. When the energization of the solenoid 33 is stopped, the connecting bar 34 is moved to the left by a tension spring (not shown) that pulls the connecting bar 34 to the left in opposition to the solenoid 33, and the transport guide 9 rotates to the right. And get up,
The upper part of the transport guide 9 contacts the sheet. Even in this case, the same effect as described above can be obtained. In the description of FIG. 4, a case has been described in which one transport guide is provided. However, a plurality of transport guides may, of course, be provided side by side in the paper width direction.

Next, a detailed operation of the image forming apparatus from automatic paper setting to printing will be described with reference to a time chart and FIGS. 5A and 5B are time charts for explaining the operation. When setting the paper automatically, first, take out the paper 1 from the hopper 2, place the paper on the tractor 5 'on the lower side of the paper transport device 5, set it, and complete the preparation for automatic paper loading. An auto load sw is pressed (on) from an operation panel (not shown) to give a start instruction.

The control device (not shown) determines whether the position of the conveyance guide 9 is at the position (on) where the conveyance guide 9 comes into contact with the sheet or the retreat position (of
f) is detected. If, as shown in FIG. 5B,
When the sensor sw1 is on, it is determined that the position of the conveyance guide 9 is a position where the conveyance guide 9 comes into contact with the sheet 1, and in order to temporarily lower the conveyance guide 9, the elevating motor 28 is moved downward (cw side). Rotate to. Next, when it is detected that the output signal of the sensor sw1 has changed from on to off, the rotation direction of the lifting / lowering motor 28 is reversed (from the cw side). ccw side), and raises the conveyance guide 9 to a position where the conveyance guide 9 contacts the sheet 1. Then, when the output signal of the sensor sw1 changes from off to on again, it is determined that the conveyance guide 9 has risen to the position where the conveyance guide 9 contacts the sheet 1, and the elevating motor 28 is stopped.
To stop.

If the output signal of the sensor sw1 is off as shown in FIG. 5A at the start of the automatic loading, it is determined at the start that the transport guide 9 is at the lowered position, and the rotational direction of the lifting motor 28 is changed. The transport guide is rotated in the upward direction (ccw side) to raise the transport guide 9 to a position where the transport guide 9 contacts the sheet 1. When the sensor sw1 changes from off to on, it is determined that the conveyance guide 9 has risen to a position where the conveyance guide 9 comes into contact with the sheet 1, and the elevating motor 28 is stopped to stop the conveyance guide 9 at that position.

On the other hand, the continuous paper 1 ready for the automatic setting is taken out of the hopper 2 by the lower tractor 5 ', which is a paper transporting device, and transported to the photosensitive drum 3, and the leading end thereof contacts the photosensitive drum 3. The transfer direction changes in the upward direction upon contact, and the sheet passes through the gap between the photosensitive drum 3 and the transfer device 4 and is guided by the upper tractor 5. Next, the continuous paper 1 is conveyed to the suction feeder 6 by the upper tractor 5 and conveyed to the fixing device 7 by the suction feeder 6. Since the conveyance guide 9 is set below the fixing device 7 at a position where the conveyance guide 9 comes into contact with the sheet 1, the conveyance guide 9 guides the sheet to a sheet conveyance roller 10 provided downstream. The paper transport roller 10 rotates slightly faster than the paper transport speed and pulls the paper in order to tension continuous paper with the suction feeder 6.

As described above, when the delivery of the continuous paper 1 to the paper transport roller 10 is completed, the continuous paper 1
At this point, the conveyance guide 9 becomes unnecessary because the paper conveyance roller 10 and the suction feeder 6 are tensioned.
Next, the continuous paper 1 is conveyed to the paper folding machine 11 by the paper conveyance roller 10, and is folded at the perforation by the paper folding machine 11 and placed on the stacker table 13.

As described above, the paper folding machine 11 is provided with the paper detector 12, and when the detector 12 detects a paper, the output of the paper detection sensor changes from off to on. Then, the control unit (not shown) determines that the paper has been automatically loaded, rotates the elevating motor 28 in the direction (cw side) to lower the transport guide, retracts the transport guide 9, and the transport guide 9 Is determined when the output signal of the switch sw2 changes from off to on, and the rotation of the elevating motor 28 is stopped. At the same time, completion of printing preparation is notified to the host device, and then printing is started.

As described above, according to the above-described method, at the time of automatic loading of paper, the continuous paper can be guided to the downstream transport roller by the transport guide. Further, at the time of printing, the transport guide is separated from the paper, and the contact between the transport guide and the back surface of the paper can be prevented, thereby preventing the printed back surface from being stained. In addition,
INDUSTRIAL APPLICABILITY The present invention is advantageous when performing back paper printing on the other side of an image forming apparatus having a double-sided printing function or on a single-sided printed sheet, and is applied to an ordinary image forming apparatus for single-sided printing. In this case, an option switch using a backing paper may be provided so that the retracting function of the transport guide is electrically turned on / off by operating the option switch.

[0024]

As is apparent from the above description, according to the present invention, even if the fixing device of the image forming apparatus becomes large for high-speed printing and the paper path becomes long, the conveyance guide is used during automatic paper loading. The automatic loading of paper can be performed accurately, while the conveyance guide is separated from the paper during printing, so it is particularly suitable for image forming equipment with double-sided printing function and backing paper printing. Thus, even if the toner on the printed back surface is melted, there is an excellent effect that both the transfer guide and the printed back surface can be prevented from being stained without touching the transfer guide.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating a main part of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating details of a transport guide according to an embodiment of the present invention.

FIG. 3 is a diagram illustrating another embodiment of the transport guide of the present invention.

FIG. 4 is a diagram illustrating another embodiment of the transport guide of the present invention.

FIG. 5 is a time chart illustrating a method for automatically setting a sheet in an image forming apparatus according to an embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 continuous paper 2 hopper 3 photosensitive drum 4 transfer device 5 paper transport device (tractor) 5 'paper transport device (tractor) 6 suction feeder 7 fixing device 8 flash lamp 9 transport guide 10 transport roller 11 swing guide 12 paper detection sensor 13 Paper Stacker 21 Transport Guide Unit 22 Supporting Member 23 Support, Supporting Member (Supporting Bar) 24 Eccentric Cam 25 Rotating Bar 26 Detection Plate 27 Gear 28 Elevating Motor 29 Gear 30 Switch 31 Switch 32 Link Fitting 33 Solenoid 34 Connecting Bar 35 Hole (Engagement part)

Claims (2)

[Claims] A fixing device for fixing a toner to a sheet by flashing a flash lamp is provided with a sheet conveying guide for conveying the sheet along a substantially constant gap, and the conveying guide is movable forward and backward. An image forming apparatus having a structure, wherein a sheet is guided by the conveyance guide only when paper is automatically loaded, and the conveyance guide is separated from the sheet in other cases. 2. A fixing device for thermally fixing toner transferred from a photoreceptor to a sheet, a sheet conveying guide on an opposite surface of the fixing device. An image forming apparatus which detects a state in which the conveyance guide is guided to a predetermined position through a gap of the image forming apparatus, and in response to the detection signal, controls the conveyance guide to retreat to a position where the conveyance guide is kept out of contact with the back surface of the sheet. Control method of paper transport guide.