JP2006243142A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inexpensively provide an image forming apparatus capable of always selecting an optimum operational condition relative to curl and realizing the stable stacking of ejected paper. <P>SOLUTION: In the image forming apparatus equipped with a double-sided image recording means, whether paper is ejected face down or face up can be selected in the case of one-side recording, and also a first recording mode being an ordinary image forming process, a second recording mode in which only the heating of recording paper is performed in a fixing part before forming the image and then the recording paper is reversed from the front side to the back side so as to form an image on an opposite side, and a third recording mode in which the recording paper on which the image is formed is reversed from the front side to the back side and then only the heating of the opposite side is performed in the fixing part can be optionally selected. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electrophotographic image forming apparatus used for a printer, a facsimile, a copying machine, and the like, and more particularly to an image forming apparatus having a double-sided recording mechanism.

Conventionally, in this type of technology, for example, Patent Literature 1 and Patent Literature 2 can be cited.
JP-A-5-165273 JP-A-6-161313

  However, among the above conventional examples, Japanese Patent Application Laid-Open No. 05-165273 is very expensive because the moisture amount of the recording paper is detected and controlled by the humidity detecting means.

  Also, the curl state does not depend only on the moisture content of the recording paper, but the environment, the type of paper, the direction of the paper gap, and the front and back of the paper. The recording paper that is ejected even after double-sided heating is in various forms such as front-rear upward, front-rear downward, left-right upward, left-right downward, and combinations thereof, so it is always optimally ejected. It was difficult to maintain the loadability.

  In Japanese Patent Laid-Open No. 06-161312, the recording paper after image formation and fixing is switched back and guided to the fixing unit again to correct the curl and eject it out of the apparatus. Therefore, the page order is reversed. There was a problem that.

  In order to solve the above problems, according to the present invention, when an image is recorded on only one side in an image forming apparatus provided with a double-sided image recording unit, an image is created on a recording sheet fed by a paper feeding unit by an image creating unit. The first recording mode in which the image is formed, fixed by the fixing unit, and discharged by the paper discharge unit, and the recording unit fed by the paper supply unit is heated only by the fixing unit without forming an image in the image forming unit. And a second recording mode for controlling to reverse the front and back by the switchback paper feeding unit, to create an image on the opposite surface by the image creating unit, to fix the image by the fixing unit, and to eject the paper by the paper ejection unit; An image is created on the recording paper fed by the image forming unit by the image creating unit, fixed by the fixing unit, turned upside down by the switchback paper feeding unit, and an image is created on the opposite side by the image creating unit. Instead, only heat at the fixing unit and A face-down discharge unit that has a control unit that selectively controls a third recording mode that controls to discharge the sheet, and discharges the sheet that has been heated last by the fixing unit downward. And a face-up discharge section that discharges the heated surface upward, and controls whether the discharge to the face-down discharge section or the face-up discharge section can be selected. The control unit controls the first, second, and third recording modes so that they can be arbitrarily selected.

  In the fixing unit, the temperature when heating the surface opposite to the recording paper surface on which the image is formed in the image forming unit is variable.

  In addition, when the discharge to the face-down discharge unit is instructed, the first or second recording mode is selected, and when the discharge to the face-up discharge unit is instructed, the third recording mode is selected. The control unit controls the recording mode to be selected.

  The paper feed unit is composed of a plurality of paper feed units so that a plurality of types of recording paper can be fed. The selection of the face-down paper discharge unit or the face-up paper discharge unit, the first, second, third The recording mode selection and the temperature setting when the fixing unit heats the surface opposite to the recording paper surface on which an image is formed in the image forming unit are controlled independently for each paper feeding unit.

  As described above, according to the present invention, in an image forming apparatus including a double-sided image recording unit, when an image is recorded only on one side, an image is formed on a recording sheet fed by a sheet feeding unit by an imaging unit. The first recording mode in which the image is formed, fixed by the fixing unit, and discharged by the paper discharge unit, and heated by the fixing unit without forming an image on the recording paper fed by the paper feeding unit And a second recording mode in which the image is reversed on the opposite side by the switchback sheet feeding unit, the image forming unit forms an image on the opposite side, the fixing unit fixes the image, and the sheet discharge unit discharges the sheet. An image is formed on the recording paper fed by the paper unit by the image forming unit, fixed by the fixing unit, the front and back sides are reversed by the switchback paper feeding unit, and an image is formed on the opposite side by the image forming unit. Without any problem, only heat at the fusing unit. A face-down discharge unit that has a control unit that selectively controls the third recording mode that controls to discharge the sheet, and discharges the sheet with the surface heated last by the fixing unit facing down; And a face-up discharge section that discharges the heated surface upward, and controls whether the discharge to the face-down discharge section or the face-up discharge section can be selected. By controlling the control unit so that the first, second, and third recording modes can be arbitrarily selected, the environment, paper type, paper gap direction, paper front and back (front and back when set in the paper feed unit) Even if the curl state changes variously depending on which direction is set), it is selected whether face-down discharge or face-up discharge, and one of the first, second and third recording modes is selected. By selecting, it is always the optimum loading condition It is possible to provide an inexpensive device for stacking sheet discharge Select.

  In addition, even if the environmental condition changes and the amount of moisture contained in the paper changes by changing the temperature when heating the surface opposite to the recording paper surface on which the image is formed in the image forming unit in the fixing unit, The surface opposite to the recording surface can be heated at a temperature suitable for curling prevention, so that it is possible to always maintain a stable discharge stackability.

  In addition, when the discharge to the face-down discharge unit is instructed, the first or second recording mode is selected, and when the discharge to the face-up discharge unit is instructed, the third recording mode is selected. By controlling the control unit so that the recording mode is selected, the sheets can be stacked without reversing the page order.

  The paper feed unit is composed of a plurality of paper feed units so that a plurality of types of recording paper can be fed. The selection of the face-down paper discharge unit or the face-up paper discharge unit, the first, second, third By independently controlling the temperature setting when the fixing unit heats the surface opposite to the recording paper surface on which an image is formed in the image forming unit, the plurality of recording modes are selected. Even when different types of recording paper are set in the paper feeding unit, it is possible to select and stack the paper with optimum conditions for each paper type.

  Hereinafter, embodiments of the present invention will be described using specific examples.

  FIG. 1 is a perspective view of a composite apparatus 1 having a printer function, a facsimile function, and a copy function to which the image forming apparatus of the present invention is applied.

  In the figure, 11 is a reading unit for reading a document S, 21 is a recording unit for recording an image read by the reading unit 11 or a facsimile received image on a recording paper P, and 31 is an operation unit for operation by a user. , 41 is a control unit for controlling printer operation, facsimile operation, and copy operation.

  FIG. 2 is a sectional view of the composite apparatus 1 to which the image forming apparatus of the present invention is applied.

  A configuration of the recording unit 21 which is a main part of the present invention will be described with reference to FIG.

  211 is a recording paper cassette for storing the recording paper P, 212 is a paper feed roller for separating and transporting the recording paper P stored in the recording paper cassette 211 one by one in cooperation with the separating member 213, and 214 is separated. A registration roller pair for correcting the skew of the recording paper P, 215 is a top sensor for detecting the leading end position of the recording paper P conveyed by the registration roller pair 214, and 216 is charged by the charging means 217 and irradiated from the laser scanner 218. A photosensitive drum on which an electrostatic latent image is formed by the image light and the toner image is developed by the developing means 219; 220, a transfer charger for transferring the toner image developed on the photosensitive drum 216 to the recording paper P; 222 Is a heat fixing unit for fixing the toner image transferred on the recording paper P conveyed through the recording paper conveyance path 221 by heating, 22 Is a paper discharge sensor that detects the end of the recording paper P discharged from the thermal fixing device 222, and 224 is a fixing discharge that holds the recording paper P together with the fixing paper discharge roller 225 and conveys it to the paper discharge conveyance path 226. A paper roller 227 is a pair of face-down paper discharge rollers capable of rotating in the forward and reverse directions. The paper roller 227 is loaded with a recording paper P discharged from the face-down paper discharge roller pair 227. The face-down paper discharge tray 229 is a pair of face-up paper discharge rollers that can be rotated in the forward and reverse directions and is discharged from the face-up paper discharge roller pair 229. The face-up discharge tray 231 on which the paper P is stacked is switched by the switching operation 231 to transfer the recording paper P to the face-down discharge roller pair 227 or face-up discharge roller pair 229. A paper discharge flapper 232 for guiding either of them is a switch for transporting the recording paper P conveyed with the face-down paper discharge roller pair 227 or the face-up paper discharge roller pair 229 reversely conveyed with the fixing paper discharge roller 224. A back roller 233 is a switch-back conveyance path for conducting the double-sided recording by guiding the recording paper P conveyed by being switched back to the registration roller pair 214 again.

  Next, the operation of a specific example according to the present invention will be described.

  When performing single-sided image recording in the image forming apparatus having the double-sided image recording mechanism as described above, according to the present invention, the following three recording modes are controlled to be selectable.

<First recording mode>
The operation in the first recording mode will be described with reference to FIG.

  When a single-side recording start signal is output from the control unit 41, the recording paper P stored in the recording paper cassette 211 is fed one by one by the paper feed roller 212 and the separating member 213 (P1).

  The fed recording paper P is corrected for skew feeding of the recording paper P by the registration roller pair 214, the leading end position is detected by the top sensor 215, and the photosensitive drum 216, the transfer charger 220, and the timing are matched. (P1).

  Thereafter, the toner image formed on the surface of the photosensitive drum 216 is transferred by the transfer charger 220 and then conveyed along the recording paper conveyance path 221, and the toner image is fixed by the thermal fixing device 222 (P2). .

  The recording sheet P on which the toner image has been fixed is conveyed along a sheet discharge conveyance path 226 by a fixing sheet discharge roller 224 and a fixed sheet discharge roller 225, and is switched to a face by a switching operation of a sheet discharge flapper 231 disposed on the downstream side. The sheet is selectively conveyed to either the down discharge roller pair 227 or the face up discharge roller pair 229 (P2).

  The recording paper P conveyed to the face-down paper discharge roller pair 227 is discharged to the face-down paper discharge tray 228, and the recording paper P conveyed to the face-up paper discharge roller pair 229 is discharged to the face-up paper discharge tray 230. (P3).

<Second recording mode>
The operation in the second recording mode will be described with reference to FIG.

  When a single-side recording start signal is output from the control unit 41, the recording paper P stored in the recording paper cassette 211 is fed one by one by the paper feed roller 212 and the separating member 213 (P4).

  The fed recording paper P is conveyed between the photosensitive drum 216 and the transfer charger 220 by the registration roller pair 214 (P4).

  However, an image is not formed on the recording paper P here, and is sent to the thermal fixing device 222 as it is (P5). The thermal fixing device 222 heats the recording paper P at a temperature controlled separately from the temperature at which the toner image is fixed, and evaporates moisture contained in the recording paper P (P5). The heating temperature at this time is controlled so as to be changeable according to the environment, the type of paper, the direction of the paper gap, the front and back of the paper (whether the paper is set in the front or back when set in the paper feed unit), etc. .

  The recording paper P whose surface has been heated is conveyed along the paper discharge conveyance path 226 by the fixing paper discharge roller 224 and the fixing paper discharge roller 225, and face down by switching operation of the paper discharge flapper 231 disposed on the downstream side. The paper is selectively conveyed to either the paper discharge roller pair 227 or the face-up paper discharge roller pair 229 (P5).

  Next, when the paper discharge sensor 223 detects that the trailing edge of the recording paper P has passed through the nip between the fixing paper discharge roller 224 and the fixing paper discharge roller 225, the face-down paper discharge roller holding the recording paper P The pair 227 or the face-up paper discharge roller pair 229 reverses, and the trailing edge of the recording paper P is conveyed to the nip between the fixing paper discharge roller 224 and the switch back roller 232, and passes through the switch back conveyance path 233 to the registration roller pair 214. The paper is fed again (P6).

  The recording paper P that has been re-fed with its front and back reversed in this way is corrected for skew of the recording paper P by the registration roller pair 214, and then the leading edge position is detected by the top sensor 215, and the timing is adjusted. It is conveyed between the body drum 216 and the transfer charger 220 (P7).

  Thereafter, the toner image formed on the surface of the photosensitive drum 216 is transferred by the transfer charger 220 and then conveyed along the recording paper conveyance path 221, and the toner image is fixed by the thermal fixing device 222 (P8). .

  The recording sheet P on which the toner image has been fixed is conveyed along a sheet discharge conveyance path 226 by a fixing sheet discharge roller 224 and a fixed sheet discharge roller 225, and is switched to a face by a switching operation of a sheet discharge flapper 231 disposed on the downstream side. The sheet is selectively conveyed to either the down discharge roller pair 227 or the face up discharge roller pair 229 (P8).

  The recording paper P conveyed to the face-down paper discharge roller pair 227 is discharged to the face-down paper discharge tray 228, and the recording paper P conveyed to the face-up paper discharge roller pair 229 is discharged to the face-up paper discharge tray 230. (P9).

<Third recording mode>
The operation in the third recording mode will be described with reference to FIG.

  When the one-side recording start signal is output from the control unit 41, the recording paper P stored in the recording paper cassette 211 is fed one by one by the paper feed roller 212 and the separating member 213 (P10).

  The fed recording paper P is corrected for skew feeding of the recording paper P by the registration roller pair 214, the leading end position is detected by the top sensor 215, and the photosensitive drum 216, the transfer charger 220, and the timing are matched. (P10).

  Thereafter, the toner image formed on the surface of the photosensitive drum 216 is transferred by the transfer charger 220, and then transferred along the recording paper transfer path 221, and the toner image is fixed by the heat fixing unit 222 (P11). .

  The recording sheet P on which the toner image has been fixed is conveyed along a sheet discharge conveyance path 226 by a fixing sheet discharge roller 224 and a fixed sheet discharge roller 225, and is switched to a face by a switching operation of a sheet discharge flapper 231 disposed on the downstream side. The sheet is selectively conveyed to either the down discharge roller pair 227 or the face up discharge roller pair 229 (P11).

  Next, when it is detected by the paper discharge sensor 223 that the trailing edge of the recording paper P having the toner image fixed on the surface has passed through the nip between the fixing paper discharge roller 224 and the fixing paper discharge roller 225, the recording paper P is sandwiched. The face-down paper discharge roller pair 227 or the face-up paper discharge roller pair 229 reversely rotates, and the rear end of the recording paper P is conveyed to the nip between the fixing paper discharge roller 224 and the switch back roller 232, and the switch back conveyance path 233. Then, the sheet is fed again to the registration roller pair 214 (P12).

  The recording paper P whose front and back are reversed in this way is conveyed between the photosensitive drum 216 and the transfer charger 220 by the registration roller pair 214 (P13).

  However, an image is not formed on the recording paper P here, and is sent to the heat fixing device 222 as it is (P14). The thermal fixing device 222 heats the recording paper P at a temperature controlled separately from the temperature at which the toner image is fixed, and evaporates moisture contained in the recording paper P (P14). The heating temperature at this time is controlled so as to be changeable according to the environment, the type of paper, the direction of the paper gap, the front and back of the paper (whether the paper is set in the front or back when set in the paper feed unit), etc. .

  The recording sheet P whose back surface is heated is conveyed along the sheet discharge conveyance path 226 by the fixed sheet discharge roller 224 and the fixed sheet discharge roller 225, and is face-down by the switching operation of the sheet discharge flapper 231 disposed on the downstream side. The paper is selectively conveyed to either the paper discharge roller pair 227 or the face-up paper discharge roller pair 229 (P14).

  The recording paper P conveyed to the face-down paper discharge roller pair 227 is discharged to the face-down paper discharge tray 228, and the recording paper P conveyed to the face-up paper discharge roller pair 229 is discharged to the face-up paper discharge tray 230. (P15).

  By selecting one of the three recording modes as described above, the curl state depends on the environment, paper type, paper gap direction, paper front and back (whether the paper should be loaded in the front or back direction) The heating temperature when selecting one of the first, second, and third recording modes and heating the surface opposite to the surface on which the toner is fixed by the thermal fixing device 222 even if the temperature changes variously. By making this variable, it is possible to always select and load the optimum stacking conditions.

  Further, in the first recording mode and the second recording mode, the face-down discharge roller pair 227 discharges to the face-down discharge tray 228, and in the third recording mode, the face-up discharge roller pair 229 faces up. By controlling the discharge to the discharge tray 230, it is possible to discharge in the page order regardless of which recording mode is selected.

  Furthermore, in this specific example, the recording paper cassettes 211 for storing the recording paper P are arranged in two upper and lower stages, and to the face-down paper discharge tray 228 independently of the paper feeding operation from each recording paper cassette 211. Selected from the sheet discharge to the face-up sheet discharge tray 230, the selection of the first, second and third recording modes, and the surface opposite to the surface on which the image is formed is heated by the heat fixing device 222. In order to control the temperature setting in this case, even when the recording paper P having a different size or type is fed, it is possible to always stack and discharge the paper under the optimum loading conditions.

1 is a perspective view of a composite apparatus to which an image forming apparatus of the present invention is applied. Sectional view of a composite apparatus to which the image forming apparatus of the present invention is applied Sectional drawing of the compound apparatus showing operation | movement of 1st recording mode Sectional drawing of the composite apparatus showing operation | movement of 2nd recording mode Sectional drawing of the compound apparatus showing operation | movement of 3rd recording mode

Explanation of symbols

211 Recording paper cassette 212 Paper feed roller 213 Separating member 216 Photosensitive drum 222 Thermal fixing device 224 Fixing paper discharge roller 227 Face-down paper discharge roller pair 228 Face-down paper discharge tray 229 Face-up paper discharge roller pair 230 Face-up paper discharge tray 231 Discharge flapper 232 Switchback roller 233 Switchback transport path

Claims (4)

A recording sheet as an image recording medium is picked up and fed one by one, and an electrostatic latent image formed on the photosensitive member is developed with toner, and formed on the photosensitive member. An image forming unit that transfers the toner image onto the recording paper, a fixing unit that heats and fixes the toner image on the recording paper formed by the image forming unit, and the recording paper after fixing is turned over to the image forming unit again. In an image forming apparatus having a double-sided image recording unit having a switchback paper feeding unit that guides and a paper ejection unit that ejects a recording paper on which an image is recorded, when an image is recorded only on one side, the paper feeding A first recording mode in which an image is formed on the recording paper fed by the image forming unit by the image forming unit, fixed by the fixing unit, and discharged by the paper discharge unit;
The recording paper fed by the paper feeding unit is heated only by the fixing unit without forming an image by the imaging unit, the front and back are reversed by the switchback paper feeding unit, and the image is formed on the opposite side. A second recording mode in which an image is formed by an image unit, fixed by the fixing unit, and discharged by the paper discharge unit;
An image is formed on the recording paper fed by the paper feeding unit by the image creating unit, fixed by the fixing unit, front and back are reversed by the switchback paper feeding unit, and the image forming unit is disposed on the opposite surface. A control unit that selectively controls a third recording mode in which only heating is performed in the fixing unit without forming an image and control is performed so that the paper is discharged by the paper discharge unit;
The paper discharge unit includes a face-down paper discharge unit that discharges paper with the surface heated last by the fixing unit facing down, and a face-up paper discharge unit that discharges paper with the last heated surface facing up. ,
The control is performed so that the paper discharge to the face-down paper discharge unit or the paper discharge to the face-up paper discharge unit can be selected, and the first, second, and third recording modes can be arbitrarily selected. An image forming apparatus controlled by a unit.   The image forming apparatus according to claim 1, wherein in the fixing unit, a temperature when heating a surface opposite to a recording paper surface on which an image is formed in the image forming unit is variable.   When discharge to the face-down discharge unit is instructed, the first or second recording mode is selected, and when discharge to the face-up discharge unit is instructed, The image forming apparatus according to claim 1, wherein the control unit controls the third recording mode to be selected.   The paper feed unit includes a plurality of paper feed units so that a plurality of types of recording paper can be fed, and the selection of the face-down paper discharge unit or the face-up paper discharge unit, the first, second, Selection of the third recording mode and temperature setting when the fixing unit heats the surface opposite to the recording paper surface on which an image is formed in the image forming unit are controlled independently for each paper feeding unit. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus.

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