JP2007147712A - Fixing device entrance guide part of image forming apparatus, image forming apparatus having fixing device entrance guide part, and entrance guide positioning program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress the temperature rise of a sheet travel surface of a fixing device entrance guide in an image forming apparatus; to place the fixing device entrance guide in such a position that the face for sheet travel of the fixing device entrance guide can be monitored from the outside of the image forming apparatus when a sheet is not traveling in the fixing device entrance guide; and to give a structure easy to clean, to the sheet travel surface to prevent the occurrence of wrinkles of conveyed sheets and the occurrence of jamming. <P>SOLUTION: The fixing device entrance guide part includes an entrance guide shaft, an entrance guide rotated around the entrance guide shaft, an entrance guide rotating mechanism, and an entrance guide control part for controlling the entrance guide rotating mechanism. The entrance guide control part puts the entrance guide to a first position for sheet passage through the entrance guide in response to reception of a signal concerning a print start signal, and the entrance guide control part rotates the entrance guide around the entrance guide shaft from the first position to a second position which is more distant from a center axis of a heat roller than the first position and is within such a range that the sheet travel surface of the entrance guide can be visually recognized from the outside of the image forming apparatus, when not receiving the signal concerning the print start signal within a certain time. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fixing device inlet for guiding a sheet to a fixing device in a printer, a copying machine, a facsimile, etc., particularly when the sheet is conveyed from a transfer device having a transfer material carrier to a fixing device having a heating roller. The present invention relates to an image forming apparatus having a guide.

  In a printer, a copying machine, a facsimile, etc., when a sheet is conveyed from a transfer device having a transfer material carrier to a fixing device having a heating roller, an image forming device having a fixing device inlet guide for guiding the sheet to the fixing device As an apparatus, FIG. 3 shows a cross-sectional view of a main part of a page printer apparatus provided with a conventional fixing device inlet guide.

In FIG. 3, the sheet conveyed from the transfer unit 11 to the fixing unit 13 through the sheet conveying unit 12 is properly placed between the heat roller (heating roller) 13-1 and the backup roller 13-2 of the fixing unit 13. A fixing device inlet guide 14 is disposed at the inlet portion of the fixing device 13 so as to be conveyed. Here, the sheet conveying unit 13 includes a belt and a roller (not shown), and conveys the sheet from the transfer unit 11 to the fixing unit 13. For example, the fixing device inlet guide 14 is fixed to the heat insulating cover 13-3 of the fixing device 13 with screws. The heat shield cover 13-3 is a heat shield member for shielding the heat radiated from the surface of the heat roller 13-1 from the inside of the heat roller 13-1 from the inside of the heat roller 13-1 from the outside of the fuser 13. It is made with.

  FIG. 4 is an explanatory diagram of a paper traveling route in the page printer apparatus provided with the conventional fixing device guide in the page printer apparatus illustrated in FIG.

  In FIG. 4, unfixed toner floats on the sheet conveyed from the transfer unit 11 to the fixing unit 13, and it is unlikely to be a problem in the case of the sheet traveling route as shown in A, but as shown in B When the paper curls and hits the sheet running surface of the fixing device entrance guide 14 (the surface of the fixing device entrance guide on the side where the paper is transported and traveled), unfixed toner adheres to the sheet running surface 14-1. When the sheet running surface 14-1 of the fixing device entrance guide 14 is heated by the heat of the heat roller 13-1 of the fixing device 13 for fixing the toner on the paper, the toner adhered to the sheet running surface 14-1. The toner melts and a lump of toner is formed on the sheet running surface 14-1 of the fixing device inlet guide 14. There is a problem in that the corners and end faces of the paper are caught in the toner mass, and the paper is wrinkled or jammed.

As a related known technique for dealing with such a problem, for example, as disclosed in Japanese Patent Application Laid-Open No. 2003-195661, the front end of an inlet guide that guides a sheet to a fixing device nip is moved to a first position and a second position. An image forming apparatus that prevents the disturbance of the toner image is shown. Japanese Patent Laid-Open No. 6-250531 sets the direction in which the extended peeling guide portion of the peeling member of the peeling device guides the paper to the fixing device, and the peeling guide member rotates to cut off the heat from the fixing device. An apparatus is disclosed.
JP 2003-195661 A JP 6-250531 A

  However, the conventional image forming apparatus has the following problems.

  For example, in the method disclosed in Japanese Patent Application Laid-Open No. 2003-195661, there is an entrance guide tip near the heated fixing roller, and switching between the first position and the second position is performed. It is considered that the toner which is heated and adheres to the front end portion of the inlet guide is melted by heat, and a problem that a lump of toner is formed at the front end portion of the inlet guide remains.

  Further, in the method disclosed in Japanese Patent Application Laid-Open No. 6-250531, the extended peeling guide portion of the peeling member of the peeling device guides the sheet to the fixing device, and the peeling guide member rotates to move from the fixing device. Although it is set in a direction to block heat, it is considered that the peeling guide part itself is placed in a heated state.

  The present invention suppresses a temperature rise on the sheet running surface of the fixing device inlet guide, and allows the sheet running surface of the fixing device inlet guide to be monitored from the outside of the image forming apparatus when the sheet is not running on the fixing device inlet guide. Another object of the present invention is to provide a structure that facilitates cleaning of the sheet traveling surface according to the degree of contamination of the sheet traveling surface, and to prevent generation of wrinkles and jamming of the conveyed sheet.

  According to a first aspect of the present invention, in the image forming apparatus, a fixing device inlet guide for guiding a sheet conveyed from a transfer device having a transfer material carrier to a fixing device having a heat roller to the fixing device. The fixing unit inlet guide portion includes an inlet guide shaft, an inlet guide that rotates about the inlet guide shaft, the inlet guide rotation mechanism, and an inlet guide control unit that controls the inlet guide rotation mechanism; And the entrance guide control unit positions the entrance guide in a first position when the sheet passes through the entrance guide by receiving a signal related to a print start signal, and the entrance guide control unit When the signal related to the print start signal is not received within a predetermined time, the inlet guide is rotated from the first position around the inlet guide shaft to be more than the first position. The fixing roller inlet is positioned at a second position away from the central axis of the heat roller, and the second position is such that the sheet running surface of the inlet guide is within a visible range from the outside of the image forming apparatus. It is a guide part.

  According to the first aspect of the present invention, the inlet guide according to the present invention is set to the first position when the sheet passes, and functions to stably feed the sheet to the fixing device.

  When the sheet is not conveyed to the fixing device within a certain time, the entrance guide turns around the entrance guide shaft and waits at the second position farther from the heat roller than the first position. ing.

  In order to move from the first position to the second position, for example, the entrance guide control unit of the fixing unit entrance guide unit receives a print activation signal from the control unit of the image forming apparatus, and controls the entrance guide of the fixing unit entrance guide unit. By the gear motor connected to the part, the inlet guide fixed to the inlet guide shaft coupled with the rotation shaft of the gear motor by the gear moves from the first position to the second position as the gear motor rotates.

  Since the inlet guide of the present invention is as described above, the influence of the heat of the heat roller can be reduced compared to the case where the inlet guide remains in the first position even when the fixing device is in a preheating standby state. Since it is in the second position where it is difficult to receive, the temperature rise can be kept low.

  In addition, when the entrance guide of the present invention is in the second position, the sheet travel surface of the entrance guide (the surface of the entrance guide on the side where the sheet is transported, the same applies hereinafter) can be monitored from the outside of the image forming apparatus. It is in the position.

  By placing the entrance guide in the second position, the temperature rise of the entrance guide is suppressed as much as possible, and the entrance guide is in a position within the range that can be monitored from the outside of the image forming apparatus according to the degree of contamination on the sheet running surface. A structure that prevents the occurrence of wrinkles and jamming of a conveyed sheet by cleaning the sheet traveling surface from the outside of the image forming apparatus, for example, by a cleaning unit provided with a wiper and keeping the sheet traveling surface clean. It has become.

  Here, when the entrance guide control unit receives a signal related to the print start signal, the entrance guide is positioned at a first position when the sheet passes through the entrance guide. For example, it may be located in a control unit of the image forming apparatus other than the fixing unit entrance guide unit. In addition to receiving a signal related to the print start signal from the control unit of the image forming apparatus by the entrance guide control unit, for example, the signal is received from a sensor that detects the leading edge of the sheet conveyed in the sheet conveyance path. It doesn't matter. Further, the signal related to the print start signal may be a signal instructed to start printing by the image forming apparatus, or a signal output from the image forming apparatus after a predetermined time based on the signal instructed to start printing. It does not matter.

  Further, the movement of the entrance guide from the first position to the second position is performed when the entrance guide control unit does not receive a signal related to the print start signal within a predetermined time, for example, in the sheet conveyance path. This is performed when a signal from a sensor for detecting the trailing edge of the sheet to be printed is not received within a predetermined time, or when a print job signal is received.

  According to a second aspect of the present invention, the inlet guide and a heat shield cover arranged around the heat roller and separated from the heat roller are coupled by a hinge mechanism, and the inlet guide shaft is connected to the hinge mechanism. The entrance shaft is moved between the first position and the second position by a rotational force of a drive motor connected to the entrance guide control unit. The fixing device inlet guide portion according to Item 1.

  According to the second aspect of the present invention, the inlet guide is coupled to the heat shield cover arranged around the heat roller by the hinge mechanism, and when the hinge shaft of the hinge mechanism rotates, the inlet guide fixed to the hinge shaft rotates. It is supposed to be.

  The entrance guide is configured to rotate around the hinge axis of the hinge mechanism by adopting a structure in which a hinge mechanism provided between the heat shield cover fixed to the image forming apparatus and the entrance guide is coupled. By mechanically fixing the heat shield cover to the image forming apparatus, the support of the inlet guide is strengthened, the number of parts can be reduced, and a simple structure can be achieved.

  According to a third aspect of the present invention, there is provided an image forming apparatus having the fixing device inlet guide portion according to the first and second aspects.

  According to the third aspect of the present invention, when the sheet is not being conveyed, the inlet guide is pivoted so that the inlet guide is placed at the second position, so that the inlet guide by heat from the heat roller of the fixing device. And a wiper from the outside of the image forming apparatus, for example, on the sheet running surface according to the degree of dirt on the sheet running surface of the entrance guide located within the monitorable range from the outside of the image forming apparatus. The image forming apparatus has a structure that prevents generation of wrinkles and jamming of a conveyed sheet by performing cleaning by a provided cleaning mechanism and keeping a sheet traveling surface clean.

  According to a fourth aspect of the present invention, there is provided an image formation having a fixing device inlet guide portion for guiding a sheet conveyed from a transfer device having a transfer material carrier to a fixing device having a heat roller to the fixing device. In the apparatus, the fixing unit inlet guide unit receives a signal related to a print start signal, and the fixing unit inlet guide unit has an inlet guide positioned at a first position when the sheet passes through the inlet guide. When the fixing unit entrance guide section does not receive a signal related to the print start signal within a predetermined time, the entrance guide is rotated from the first position about the entrance guide shaft to And a step of positioning at a second position further away from the center axis of the heat roller than the position, and the second position is the image of the sheet running surface of the inlet guide. It is the entry guide positioning method, characterized in that from the outside of the forming device in the visible range.

  According to a fifth aspect of the present invention, there is provided an image formation having a fixing device inlet guide portion for guiding a sheet conveyed from a transfer device having a transfer material carrier to a fixing device having a heat roller to the fixing device. An inlet guide positioning program for the apparatus, comprising: a step of receiving a signal related to a print activation signal by the fixing device inlet guide unit in a computer; and a step of receiving the signal related to the print activation signal in the fixing device inlet guide unit. Positioning the inlet guide at a first position when the sheet passes through the inlet guide; and when the fixing unit inlet guide portion does not receive a signal related to the print start signal within a predetermined time, the inlet guide Is rotated from the first position about the inlet guide shaft so as to be further away from the center axis of the heat roller than the first position. A second positions, said second position is an inlet guide positioning program for executing the steps of sheet running surface of the inlet guide is positioned from the outside of the image forming apparatus to a position that is in the visible range.

  According to the present invention, when the entrance guide is in the second position, the temperature increase of the entrance guide due to heat generated from the heat roller of the fixing device can be suppressed, and the sheet running surface of the entrance guide is visible from the outside of the image forming apparatus. Therefore, the sheet traveling surface of the entrance guide can be easily monitored from the outside of the image forming apparatus, and the sheet traveling surface can be cleaned as necessary. The generation of wrinkles and jams can be prevented, and stable fixing can be achieved.

FIG. 1 shows an embodiment of an inlet guide according to the invention. In the drawing, a cross-sectional view of the main part of the image forming apparatus in which the inlet guide 4-2 is illustrated is shown.
The transfer device 1 includes a transfer drum 1-1 and a transfer roller, and a sheet conveyed from the transfer device 1 through the sheet conveyance unit 2 to the fixing device 3 is a heat roller (heating roller) 3 of the fixing device 3. An inlet guide 4-1 is disposed at the inlet portion of the fixing device 3 so as to be properly conveyed between the first roller 1 and the backup roller 3-2. Here, the sheet conveying unit 2 includes a belt and a roller (not shown), and conveys the sheet from the transfer device 1 to the fixing device 3.

  The fixing device inlet guide section 4 includes an inlet guide 4-1, an inlet guide shaft 4-2, a gear motor (not shown) provided on the rear surface of the drawing for rotationally driving the inlet guide shaft 4-2, and inlet guide control. Has a part.

  The entrance guide 4-1 is made of a metal such as an aluminum alloy plate or a stainless steel plate, for example, and is held at the first position at the time of sheet conveyance. 4-3 is held facing the sheet conveying unit 3.

  The fixing device inlet guide portion 4 is in contact with the end surface of the fixing device 3 with the inlet guide shaft 4-2 as a fulcrum, and the inlet guide shaft 4-2 rotates clockwise in FIG. It can be done.

  FIG. 2 shows an embodiment (standby state) of the inlet guide according to the present invention. In this figure, the inlet guide 4-1 is rotated from the first position in FIG. 1 around the inlet guide shaft 4-2, and the inlet guide 4-1 is moved to the second position. Is held at the standby position. The sheet running surface 4-3 of the fixing device inlet guide 4 is held substantially perpendicular to the horizontal surface of the sheet conveying unit 3.

  As can be seen from this figure, the entrance guide 4-1 is located farther from the heat roller 3-1 of the fixing device 3 than the first position shown in FIG. Since the heat to the inlet guide 4-1 is shielded by the tip of 3-3, the temperature rise of the inlet guide 4-1 is suppressed, and the sheet running surface 4-3 is visible from the outside of the image forming apparatus. Since it is within the range, the degree of contamination of the sheet traveling surface 4-3 can be easily monitored, and the sheet traveling surface 4-3 can be easily cleaned from the outside of the image forming apparatus.

  Here, a mechanism for rotating the inlet guide 4-1 (not shown in FIGS. 1 and 2) will be described with reference to the rotational operation explanatory view of the inlet guide according to the present invention in FIG.

  FIG. 5 is a view as viewed from the opposite side of the paper surface of FIGS. 1 and 2, and the fixing device inlet guide portion 4 includes an inlet guide 16, a gear 17, a gear motor 18, a notched disk 19, a photo sensor 20, and a support pin. 21. The inlet guide control unit included in the fixing unit inlet guide unit 4 is not shown. The fixing device inlet guide unit 4 may be placed in a control unit of an image forming apparatus (not shown).

  The support pin 21 has a D-cut portion 21-1 having a flat portion formed on a part of the outer periphery of the cylinder and a D-shaped cross section perpendicular to the axial direction. It is thinner than the D-cut portion 21-1. A D-shaped hole through which the D-cut portion 21-1 passes is provided at the center of the notched disc 19 that detects the position of the support pin 21 in the rotational direction. The notched disc 19 is a D-cut portion of the support pin 21. It is being fixed to the outer periphery of 21-1. Further, a photosensor 20 that detects a notch provided on the outer periphery of the notched disk is disposed in a non-contact manner with respect to the notched disk 19.

  Next, a D-shaped hole through which the D-cut portion 21-1 passes is provided at the center, and the gear 17 is fixed to the outer periphery of the D-cut portion 21-1 of the support pin 21. The gear 17 meshes with a gear fixed to the rotation shaft of the gear motor 18, and the gear motor 18 is attached and fixed to a substrate (not shown) of the image forming apparatus. Further, the inlet guide 16 is provided with a D-shaped hole through which the D-cut portion 21-1 passes in a side surface in a direction perpendicular to the axis of the support pin 21, and driven into the outer periphery of the D-cut portion 21-1 of the support pin 21. It is fixed. The cylindrical shaft portion 21-2 of the support pin 21 passes through the hole portion 15-1 of the heat shield cover 15, and the fixing device inlet guide portion 4 is rotatably attached to the heat shield cover 15 fixed to the image forming apparatus. ing.

  Here, the support pin 21 is the inlet guide shaft 4-2 in FIGS. 1 and 2, and a hole 15-2 (not shown) is provided in the heat shield cover 15 on the opposite side of the heat shield cover 15. 15-1 is provided symmetrically. Further, the D cut hole 22-2 (not shown) is provided on the opposite side of the entrance guide 16 symmetrically with the D cut hole 22-1.

  Here, the cylindrical shaft portion 21-2 of the support pin 21 is omitted and is shown in a short form, but the tip of the support pin 21 reaches a hole portion 15-2 (not shown) provided in the heat shield cover 15 and is freely rotatable. It is supported.

  Since the inlet guide 16 in FIG. 5 has the above-described structure, the fixing unit inlet guide portion 4 excluding the gear motor 18 and the inlet guide control unit (not shown) is insulated by the rotational driving force of the gear motor 18. The support pin 21 rotates with respect to the cover 15 as a rotation axis, and is rotated by a photosensor 20 that detects two cutout portions 19-1 and 19-2 provided on the outer periphery of the cutout disc 19. The position is detected, and the start and stop of the drive are controlled by the entrance guide control unit.

  FIG. 6 is a time chart showing the operation of the fixing device inlet guide portion according to the present invention.

  6, as shown in step (a), for example, when the printer apparatus is turned on at time T1, the gear motor 18 in FIG. 5 instructs the entrance guide control unit in step (b). The gear 17 starts to rotate in the clockwise (+) direction, and the gear 17 rotates counterclockwise. At time T2, the photosensor 20 moves the notched portion 19-2 of the notched disc 19 in step (c). When detected, the inlet guide control unit stops the gear motor 18. At this time, the inlet guide 16 of FIG. 5 is held in the second position.

  Subsequently, at time T3, in step (d), the inlet guide control unit detects the leading edge of the sheet conveyed from the transfer unit by a fixing unit inlet sensor (not shown) attached to the conveyance unit of the printer apparatus. Then, the gear motor 18 starts to rotate in the counterclockwise (−) direction according to the instruction from the inlet guide control unit, and the gear 17 rotates the inlet guide 16 in the clockwise direction. At the time T4, the notched portion of the notched disc 19 is obtained. When the photosensor 20 detects 19-1, the inlet guide control unit stops the gear motor 18. At this time, the inlet guide 16 shown in FIG. 5 is held at the first position and is held at a position where the sheet is conveyed to the fixing device.

  Further, even at time T5 of a predetermined time from time T3, that is, in step (d), the fixing device inlet sensor (not shown) in which the inlet guide control unit is attached to the conveying unit of the printer is transferred. If the fuser entrance sensor does not detect the leading edge of the paper conveyed from the transfer device even after a predetermined time has elapsed since the trailing edge of the paper conveyed from the transfer device has been detected, the gear motor 18 in FIG. The gear 17 starts rotating in the clockwise (+) direction in response to an instruction from the inlet guide control unit, and the gear 17 rotates counterclockwise. At time T6, the photosensor 20 detects the notch 19-2 of the notched disc 19. Then, the inlet guide control unit stops the gear motor 18 and the inlet guide 16 shown in FIG. 5 is held in the second position again.

  Further, when the power of the printer apparatus is turned off, the entrance guide control unit causes the gear motor 18 to hold the entrance guide in the first position as an end process, and the process ends.

  Here, the entrance guide control unit receives a signal for detecting the leading edge and the trailing edge of the paper conveyed from the transfer device by the fixing device inlet sensor, and instead of rotating and stopping the gear motor 18, for example, The gear motor 18 may be rotated and stopped in response to the print job start signal and the print job end signal.

An embodiment of an inlet guide according to the present invention One embodiment of the inlet guide according to the present invention (standby state) Sectional view of the main part of a page printer device equipped with a conventional fixing device inlet guide Is an explanatory diagram of a paper travel route in a page printer apparatus provided with a conventional fixing device inlet guide. Is an explanatory view of the rotation operation of the inlet guide according to the present invention. Is a time chart showing the operation of the fixing device inlet guide portion according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,11 Transfer device 2,12 Sheet conveyance part 3,13 Fixing device 4,14 Fixing device inlet guide part 15 Heat shield cover 16 Entrance guide 17 Gear 18 Gear motor 19 Notched disk 20 Photo sensor 21 Support pin

Claims (5)

In the image forming apparatus,
A fixing device inlet guide for guiding a sheet conveyed from a transfer device including a transfer material carrier to a fixing device including a heat roller to the fixing device;
The fixing device inlet guide portion includes an inlet guide shaft,
An inlet guide that rotates about the inlet guide shaft;
The inlet guide rotation mechanism;
An inlet guide controller for controlling the inlet guide rotation mechanism,
The entrance guide control unit positions the entrance guide at a first position when the sheet passes through the entrance guide by receiving a signal related to a print start signal,
When the entrance guide control unit does not receive a signal related to the print start signal within a predetermined time, the entrance guide control unit rotates the entrance guide from the first position about the entrance guide shaft to make it more than the first position. Positioned at a second position away from the central axis of the heat roller;
The fixing unit inlet guide portion, wherein the second position is such that a sheet running surface of the inlet guide is in a visible range from the outside of the image forming apparatus.   The entrance guide and a heat shield cover disposed around the heat roller and separated from the heat roller are coupled by a hinge mechanism, and the entrance guide shaft is a hinge shaft of the hinge mechanism, and the entrance guide is 2. The fixing device inlet guide portion according to claim 1, wherein the fixing device inlet guide portion moves between the first position and the second position by a rotational force of a driving motor connected to the inlet guide control portion.   An image forming apparatus having the fixing device inlet guide portion according to claim 1. In an image forming apparatus having a fixing device entrance guide for guiding a sheet conveyed from a transfer device having a transfer material carrier to a fixing device having a heat roller to the fixing device,
The fixing unit entrance guide unit receiving a signal related to a print activation signal;
Positioning the inlet guide of the fixing device inlet guide portion at a first position when the sheet passes through the inlet guide;
When the fixing unit entrance guide unit does not receive a signal related to the print start signal within a predetermined time, the entrance guide is rotated from the first position around the entrance guide shaft to move from the first position. Positioning at a second position further away from the central axis of the heat roller,
The entrance guide positioning method, wherein the second position is such that a sheet travel surface of the entrance guide is in a visible range from the outside of the image forming apparatus. An inlet guide positioning program for an image forming apparatus having a fixing device inlet guide portion for guiding a sheet conveyed from a transfer device having a transfer material carrier to a fixing device having a heat roller to the fixing device. ,
The fixing unit entrance guide unit receiving a signal related to a print activation signal;
Positioning an inlet guide of the fixing device inlet guide portion at a first position when the sheet passes through the inlet guide by receiving a signal related to the print activation signal;
When the fixing unit entrance guide unit does not receive a signal related to the print start signal within a predetermined time, the entrance guide is rotated from the first position around the entrance guide shaft to move from the first position. A second position further away from the central axis of the heat roller, wherein the second position is positioned at a position where the sheet travel surface of the inlet guide is within a visible range from the outside of the image forming apparatus. Entrance guide positioning program to be executed.

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