JP2008151922A - Fixing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a fixing film from, for example, being torn or bent, by easily removing a jam without soiling a paper ejection roller, paper ejection roll, fixing film, pressure roller, etc., and reducing damage to a film, and so on arising during the removal of a jam. <P>SOLUTION: The fixing device is configured such that the sandwiching parts of a fixing means are separated in synchronization with the operation of canceling the fixing means and, in addition, the sandwiching parts of a paper ejecting means are separated. A pair of guide means are provided for guiding the leading end of a sheet to the nip of the paper ejecting means. In addition, an interval between the guide means is increased in synchronization with the operation of separating the fixing means as well as the paper ejecting means. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fixing device provided in an image forming apparatus such as a copying machine, a printer, or a facsimile that employs an electrophotographic system.

  An electrophotographic image forming apparatus is provided with a fixing device for fixing an unfixed toner image transferred onto a sheet to the sheet surface. It has come to pass.

  FIG. 3 shows a configuration of a conventional fixing device.

  The fixing device 100 </ b> D includes a fixing unit 101 that fixes a toner image and a paper discharge unit 102 that discharges a sheet that has passed through the identification attaching unit 101.

  The means 101 includes a pressure roller 103 that rotates counterclockwise, and a plate-like heater 104 that is in contact with the pressure roller 103 with a predetermined pressure.

  The pressure roller 103 is rotatably attached to a predetermined position of the lower frame 105. Driving from a driving source (not shown) is transmitted to the pressure roller 103. The heater 104 is attached to a film guide 107 portion integrated with the heater stay 106. A cylindrical film 108 is fitted on the outer peripheral surface of the film guide 107 in a rotatable state. This film 108 covers the heater 104. The heater stay 106 is attached to the lower frame 105 so as to be movable in the vertical direction.

  The heater stay 106 is biased toward the pressure roller 103 by a biasing spring (coil spring) 110 attached to the upper frame 109. As a result, the heater 104 comes into contact with the pressure roller 103 through the film 108 with a predetermined pressure. The biasing spring 110 abuts on the heater stay 106 via the spring seat member 111.

  The upper frame 109 is rotatable in the vertical direction about the rotation center 105 a of the lower frame 105. FIG. 3A shows a state in which the upper frame 109 is closed at a predetermined position. In this state, the urging spring 110 urges the heater stay 106 toward the pressure roller 103, and the heater 104 contacts the pressure roller 103 with a predetermined pressure via the film 108 to form a fixing nip portion. When the upper frame 109 is closed at a predetermined position, it is locked to the lower frame 105 by a locking means (not shown).

  The paper discharge means 102 includes a paper discharge roller 112 that rotates counterclockwise, and a paper discharge roller 113 that rotates in contact with the paper discharge roller 112 with a predetermined pressure.

  The paper discharge roller 112 is rotatably attached to a predetermined position of the lower frame 105. Drive from a drive source (not shown) is transmitted to the paper discharge roller 112. The paper discharge roller 113 is rotatably attached to the lower frame 105 via a paper discharge upper guide member 114. The sheet discharge upper guide member 114 is fixed to the lower frame 105. The sheet discharge roller 113 is attached to the sheet discharge upper guide member 114 so as to be movable in the vertical direction, and is urged toward the sheet discharge roller 112 by a biasing spring (plate spring) 115. As a result, the paper discharge roller 113 is in contact with the paper discharge roller 112 at a predetermined pressure.

  Reference numeral 116 in the figure denotes an inlet guide member for guiding the leading edge of the sheet to the nip of the fixing means 101, and reference numeral 117 denotes a discharge guide for guiding the leading edge of the sheet to the nip of the discharging means 102 as a pair with the upper discharge guide member 114. It is a paper lower guide member. The inlet guide member 116 and the paper discharge lower guide member 117 are fixed to the lower frame 105.

  FIG. 3A shows a state in which the fixing device 100D is operating.

  Drive from a drive source (not shown) is transmitted to the pressure roller 103, and the pressure roller 103 rotates counterclockwise. The film 108 rotates around the film guide 107 following the rotation of the pressure roller 103. The heater 104 is energized, and a temperature detection element (not shown) is brought into contact with the back surface of the heater 104 to adjust the temperature to a predetermined temperature. The heat of the heater 104 is transmitted to the sheet through the film 108.

  Drive from a drive source (not shown) is transmitted to the paper discharge roller 112, and the paper discharge roller 112 rotates counterclockwise. The paper discharge roller 113 is rotated following the rotation of the paper discharge roller 112.

  The leading edge of the sheet S after the transfer of the toner image is guided to the entrance guide member 116 and enters the nip of the fixing unit 101, and the sheet S is conveyed in a state of being sandwiched by the fixing unit 101 with a predetermined pressure. During this conveyance, the sheet S is heated and pressurized, and an unfixed toner image on the sheet S is fixed on the sheet surface.

  The leading edge of the sheet S that has passed through the fixing unit 101 is guided to the discharge upper guide member 114 and the lower discharge guide member 117 and enters the nip of the discharge unit 102, and the sheet S is applied to the discharge unit 102 with a predetermined pressure. The paper is ejected outside the machine while being held.

When a jam occurs in the sheet S passing through the fixing device 100D, the clamping pressure of the fixing unit 101 is released, and the jammed sheet is pulled out in the sheet conveying direction or the direction opposite to the sheet conveying direction. In order to release the clamping pressure of the fixing unit 101, the upper frame 109 released from the locked state may be rotated upward about the rotation center 105a of the lower frame 105. By doing so, the biasing force applied to the heater stay 106 by the biasing spring 110 is released, so that the contact pressure (clamping pressure) of the heater 104 to the pressure roller 103 becomes very small. FIG. 3B shows a state in which the upper frame 109 is rotated upward to release the clamping pressure of the fixing unit 101.
Japanese Patent Laid-Open No. 10-123877

  However, in the case of the fixing device 100D of the conventional example, the sheet discharge means 102 holds the sheet with a predetermined pressure without changing the sheet discharge operation even during the jam processing, and the following problems occur. It was. That is, when an attempt is made to pull out a jammed sheet whose leading end has passed through the nip of the sheet discharge means 102 in the sheet conveyance direction, the sheet discharge roller 113 becomes a load and cannot be pulled out smoothly. In this case, the drive of the paper discharge roller 112 is released, and the paper discharge roller 112 is freely rotatable in the sheet conveyance direction. When the jammed sheet whose leading end passes through the nip of the paper discharge means 102 is pulled out in the sheet conveyance direction, the paper discharge roller 113 moves on the jam sheet, so that unfixed toner adheres to the paper discharge roller 113. . In this state, the toner attached to the paper discharge roller 113 stains the next sheet, so the toner attached to the paper discharge roller 113 must be cleaned. Even if an attempt is made to pull out a jammed sheet whose leading end has passed through the nip of the sheet discharge means 102 in a direction opposite to the sheet conveying direction, the sheet discharge roller 112 and the sheet discharge roller 113 are loaded, and it is difficult to pull out. In this case, the discharge roller 112 is in a state where the drive is transmitted and cannot be freely rotated.

  Japanese Patent Laid-Open No. 10-1860176 includes a fixing unit that fixes a toner image with a sheet held at a predetermined pressure, and a sheet discharging unit that discharges a sheet with the sheet held at a predetermined pressure. A configuration is provided in which the clamping pressure of the paper discharge unit is released in conjunction with the operation of releasing the clamping pressure of the unit. However, in the previously proposed state, the clamping pressure between the fixing film 103 and the pressure roller 108 is related. Is configured to release only the nipping pressure. If an unfixed image is on the jam sheet, it will adhere to the fixing film 103 or the pressure roller 108 during the jam processing, so that the next paper passed through There is a risk that toner adheres to the front and back surfaces of the toner. Further, when the jam sheet is jammed in such a state that the applied pressure is present, the fixing film 103 having a thin film structure is subjected to an external force by the jam processing in a direction (longitudinal direction) other than the original rotation direction of the fixing film 103. A load may be generated, and the fixing film 103 may be damaged. Therefore, according to the present invention, the jammed sheet whose leading end passes through the nip of the sheet discharge means can be easily pulled out in either the sheet conveying direction or the conveying direction opposite to the sheet conveying direction. It is possible to provide a fixing device in which unfixed toner does not adhere to the fixing unit when the toner is pulled out. Further, it is possible to provide a fixing device that can easily remove a jam sheet without being influenced by the drawing state (direction and force) of the sheet at the time of jam processing and can perform jam processing without causing damage to the fixing film 103.

In a fixing device comprising: a fixing unit that fixes a toner image with a sheet held at a predetermined pressure; and a paper discharge unit that discharges a sheet with a sheet held at a predetermined pressure.
The holding unit of the fixing unit and the holding unit of the paper discharge unit are separated from each other in conjunction with the operation of releasing the fixing unit.

  As described above, in the fixing device of the present invention, the nipping pressure of the paper discharge unit and the fixing unit is released and separated in conjunction with the operation of releasing the nipping pressure of the fixing unit. The jammed sheet passing through the nip of the paper means can be easily pulled out in either the sheet conveying direction or the direction opposite to the sheet conveying direction. Further, even if the jammed sheet is pulled out in the sheet conveying direction, unfixed toner does not adhere to the paper discharge means and the fixing means, so there is no need for cleaning.

  In the fixing device of the present invention, the gap between the pair of guide means for guiding the leading edge of the sheet to the nip of the paper discharge means is increased in conjunction with the operation for releasing the clamping pressure of the fixing means, so that the jam processing is performed. It becomes easy.

  Furthermore, since the load on the fixing member (film or pressure roller) is reduced during the jam processing, these members are not damaged.

(Example 1)
FIG. 2 shows an example of the overall configuration of a copying machine (image forming apparatus) provided with the fixing device 100A of the present invention.

  In the present copying machine, documents are set one by one on a document table 202 by an automatic document feeder (ADF) 201 provided at the top of the copying machine main body 200.

  Documents (not shown) stacked on the paper feed tray 203 of the automatic document feeder 201 are fed one by one onto the document table 202 by the document feeder 204. The document fed onto the document table 202 is set at a predetermined position on the document table 202 by the transport belt 205. Immediately after this, the optical system 206 operates to read the image of the document on the document table 202. Then, the document whose image has been read on the document table 202 is discharged onto the discharge tray 207 by the transport belt 205.

  An image read by the optical system 206, that is, image light, is projected onto the photosensitive drum 208 rotating in the clockwise direction. Thus, an electrostatic latent image is sequentially formed on the photosensitive drum 208, and the electrostatic latent image is visualized (toner image) with toner supplied from the developing device 209.

  In the copying machine main body 200 of the present copying machine, two automatic paper feeding units, a paper feeding cassette 210 and a paper deck 111, are provided, and the sheet S of one of the paper feeding units is selectively fed. It is like that. The manual feed tray 212 can manually feed sheets one by one.

  The sheet S fed from the paper feed cassette 210, the paper deck 211, or the manual feed tray 212 reaches the registration roller pair 213 in a rotation stopped state, and the leading edge of the sheet hits the nip of the registration roller pair 213, thereby causing a predetermined amount of loop. Stops moving once formed. Thereby, the skew state of the sheet S is corrected.

  The sheet S that has been corrected in the skew state is transferred between the photosensitive drum 208 and the transfer charger 214 by the registration roller pair 213 that starts rotating at the timing of aligning the position with the toner image on the photosensitive drum 208. It is sent to the department. Then, the toner images on the photosensitive drum 208 are sequentially transferred by the transfer charger 214 to the sheet S passing through the transfer portion.

  The sheet S that has passed through the transfer portion is peeled off from the photosensitive drum 208 by the separation charger 215 and conveyed to the fixing device 100A of the present invention by the conveyance belt 216. The fixing process in the fixing device 100A is performed as described above.

  The sheet S that has undergone the toner image fixing process in the fixing device 100A is discharged onto a discharge tray 219 outside the apparatus by a discharge roller pair 218 and the like.

  FIG. 1 shows a configuration of a fixing device according to a first embodiment of the present invention. Here, FIG. 1A shows a state during the fixing operation, and FIG. 1B shows a state during the jam processing.

  In the description of the configuration of the fixing device 100A, the same members and the like as those of the fixing device 100D of the conventional example are given the same reference numerals, and the descriptions of those that are not structurally and functionally changed are omitted. .

  In the fixing device 100A, the upper discharge guide member 114 holding the discharge roller 113 is fixed to the upper frame 109 so that the discharge roller 113 moves integrally with the upper frame 109. Further, in the present fixing device 100A, the sheet guide roller 113 is moved together with the upper frame 109 by a separation lever 130 that fixes the film guide 107 that supports the fixing film 107 to the upper frame 109. . The separation lever 130 is configured not to be in contact with the film guide 107 in the state of FIG. 1A so that the applied pressure is not impaired in a normal fixing state. Then, at the same time when the upper frame 109 moves during the jam processing, it is configured such that it first comes into contact with the film guide 107 and is separated from the pressure release and pressure roller 103.

  That is, as shown in FIG. 1A, in a state where the upper frame 109 is closed and locked, the discharge roller 113 is urged by the urging spring 115 and contacts the discharge roller 112 with a predetermined pressure. ing. Further, the fixing film 107 and the heater 104 are biased by a biasing spring 110 and are in contact with the pressure roller 103 with a predetermined pressure. However, when the upper frame 109 is rotated upward for jamming, as shown in FIG. 1B, the paper discharge roller 113 is separated from the paper discharge roller 112 and the fixing film 107 is moved to the pressure roller 103. Separate.

  Therefore, it is possible to easily pull out the jammed sheet having the leading end of the sheet passing through the nip of the sheet discharge unit 102 in either the sheet conveying direction or the direction opposite to the sheet conveying direction. Further, even if the jammed sheet is pulled out in the sheet conveying direction, unfixed toner does not adhere to the paper discharge roller 113 and the fixing film 107, so that cleaning is not necessary. Further, since the space between the paper discharge upper guide member 114 and the paper discharge lower guide member 117 is widened, it is easy to perform jam processing. The fixing device in this embodiment has a temperature detection element attached to the back surface of the heater in order to permanently fix the toner image on the sheet, and the heater temperature control is performed based on the information of the temperature detection element. In the heater temperature control, the temperature is raised to the fixing temperature adjustment temperature by a current supplied from a current supply unit (not shown). This current is generated from a commercial power source. Therefore, in order to improve the safety at the time of jam processing, in this embodiment, at the time of jam processing, the current supply from the previous current supply means is cut off and the current supply to the heater is stopped at the same time. By doing so, the user's jam handling action is safely performed. Although not used in this embodiment, the image forming apparatus has a current supply device other than the current supply to the heater. For example, a voltage is supplied to a fixing film included in the fixing device, a voltage is supplied to a pressure roller, or a voltage is supplied to a fixing inlet guide. Although the purpose of these uses will not be described in this embodiment, there is a possibility that the user may come in contact with these members at the time of jam processing, and the current and voltage supply to the members and parts that operate the device are cut off at the same time. It is still safer to do.

  In addition, a means (not shown) for applying a bias to at least one of the paper discharge roller 112 and the pressure roller 103 or the fixing film 107 so that the paper discharge roller 112 and the pressure roller 103 or the fixing film 107 have the same potential. It is safer to cut off the bias applied to the jam during jam processing.

(Example 2)
FIG. 4 shows the configuration of the fixing device according to the present embodiment. Here, FIG. 4A shows a state during the fixing operation, and FIG. 4B shows a state during the jam processing.

  In the description of the configuration of the fixing device 100C, the same members and the like as those of the fixing device 100D of the conventional example are given the same reference numerals, and descriptions of components that are not structurally and functionally changed are omitted. .

  In the fixing device 100C, the separation between the paper discharge roller 112 and the paper discharge roller 113 in conjunction with the operation of opening the fixing rear cover 140 disposed on the back surface of the fixing device, and the separation between the fixing film 107 and the pressure roller 103. It is configured to do. The fixing rear cover 104 is provided with a fulcrum 141 for opening and closing and a fulcrum 142 of the opening and closing column 150. One end of the opening / closing column 150 acts as a fulcrum 142 and rotates in conjunction with opening / closing of the fixing rear cover 140. On the other hand, the other end of the open / close column 150 is disposed at a position where it comes into contact with the upper frame. When performing jam processing with such a configuration, first, the fixing cover 140 opens with the fulcrum 140 as a shaft. Along with this operation, the fulcrum 141 becomes a fulcrum, and the vicinity of the fulcrum 142 of the fixing cover 140 acts on the open / close column 150 as an action point. The force at the action point is converted into a force in the direction in which the open / close column 150 opens the upper frame 109. That is, by opening the fixing cover 140, the paper discharge roller 112 and the paper discharge roller 113 are separated from each other, and the fixing film 107 and the pressure roller 103 are separated from each other. In the first embodiment, it is necessary to open and close the upper frame 109 directly by the user at the time of jam processing. In this operation, the user may come into contact with the upper frame 109 and there is a risk of danger. However, jam processing can be performed safely and easily by using this embodiment.

1 is a longitudinal side view showing a configuration of a fixing device according to a first embodiment of the present invention. 1 is a longitudinal side view showing an example of the overall configuration of a copying machine (image forming apparatus) provided with a fixing device of the present invention. Sectional drawing of the conventional fixing device. FIG. 6 is a longitudinal side view showing a configuration of a fixing device according to a second embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100A Fixing device 100B Fixing device 100C Fixing device 101 Fixing means 102 Paper discharge means 114 Paper discharge upper guide member (guide means)
117 Discharge lower guide member (guide means)
130 Separation lever 140 Fixing rear cover 150 Opening / closing post 208 Photosensitive drum (toner image carrying means)
214 Transfer charger (transfer means)
S sheet

Claims (5)

In a fixing device comprising: a fixing unit that fixes a toner image with a sheet held at a predetermined pressure; and a paper discharge unit that discharges a sheet with a sheet held at a predetermined pressure.
A fixing device, wherein the fixing unit and the paper discharge unit are separated from each other in conjunction with an operation of releasing the fixing unit.   In addition to having a pair of guide means for guiding the leading edge of the sheet to the nip of the paper discharge means, the gap between the guide means is widened in conjunction with the operation of releasing the pinching pressure of the fixing means and the pinching pressure of the paper discharge means. The fixing device according to claim 1, wherein the fixing device is configured as described above.   3. The fixing unit according to claim 1, wherein the toner image carrying unit carries a toner image, the transfer unit transfers the toner image carried on the toner image carrying unit onto a fed sheet, and the fixing unit according to claim 1. And an image forming apparatus.   The image forming apparatus according to claim 3 further includes a fixing heater for fixing the toner image, and a current supply device for increasing the temperature of the heater, and the current of the current supply device is An image forming apparatus wherein temperature control of the fixing unit is performed based on information of a temperature detection unit included in the unit.   The fixing device according to claim 1 or 2 includes at least a heat fixing member and a pressure member, and a conductive member is provided on a paper discharge side of a heating nip formed by the member, and the member and the conductive member are provided. An image forming apparatus comprising means for applying a bias to at least one of the same potential.

Images