`ECBQRTQLJ / —
Contents
1. different from the first embodiment thus the second embodiment achieves a quick jam process and a simple operation The third embodiment shown in FIG 6 includes the step of judgement on whether or not the hinged door is opened in addition to the steps for the first embodiment The fourth embodiment shown in FIG 7 also includes the step of judgement on whether or not the hinged door is opened in addition to the steps for the second embodiment In FIG 6 for a control operation to the cooling mechanism of the fixing device in the third embodiment it is judged whether or not jamming occurs in the fixing device in step ST11 by means of a detection signal from the jam detecting sensor 16 Judged next is whether or not a user has opened the hinged door in step ST11 If the hinged door is judged as being opened the process follows the same steps shown in FIG 4 for the first embodiment A cooling operation con tinues to a jamming paper while the forced cooling button 18 has been continuously depressed and when the button 18 is released in step ST4 the forced cooling fan 17 is stopped in step STS Judgement on whether or not the front hinged door of the image forming apparatus 1 is opened is made by means of a detection signal from a sensor to detect contact between the apparatus body and the door FIG 7 shows a flow chart for a control operation in the fourth embodiment like the third embodiment shown in FIG 6 in which the forced cooling2. 374 063 B1 FIG 2 U S Patent Apr 16 2002 Sheet 3 of 8 US 6 374 063 B1 10 iQ z FIG 3 U S Patent Apr 16 2002 Sheet 4 of 8 US 6 374 063 B1 START YES ST 2 FORCED COOLING NO BUTTUN DEPRESSED YES DRIVE FORCED COOLING FAN cis ST4 FORCED COOLING FAN YES CONTINUOUSLY DEPRESSED NO FIG 4 U S Patent Apr 16 2002 Sheet 5 of 8 US 6 374 063 B1 START YES ST2 NO FORCED COOLING BUTTUN DEPRESSED YES DRIVE FORCED COOLING FAN SET TIME ELAPSED YES FIG 5 U S Patent Apr 16 2002 Sheet 6 of 8 US 6 374 063 B1 START ee YES HINGED ve OR OPENED YES FORCED COOLING BUTTON aac YES DRIVE FORCED COOLING FAN FORCED COOLING FAN CONTINUOUSLY DEPRESSED NO FORCED COOLING FAN STOPPED FIG 6 U S Patent Apr 16 2002 Sheet 7 of 8 US 6 374 063 B1 START ST NO YES one HINGED DOOR OPENED No YES ST 2 FORCED COOLING NO BUTTON DEPRESSED YES ST 1O NO SET TIME ELAPSED YES END FIG 7 U S Patent Apr 16 2002 Sheet 8 of 8 US 6 374 063 B1 START ST kaa j YES DRIVE FORCED COOLING FAN ST3 ST 10 NO SET TIME ELAPSED YES FIG 8 US 6 374 063 B1 1 FIXING DEVICE USED FOR IMAGE FORMING APPARATUS BACKGROUND OF THE INVENTION The present invention relates to an image forming appa ratus such as a plane paper color copy machine and a printer fo
3. drive admitting unit for automatically admitting the cooling means to be driven according to a predeter mined control signal after the jam has been detected by the jam detecting means and said fixing device further comprising a manual drive admitting for manually admitting the cooling means to be driven by controlling the automatic drive admitting unit the manual drive admitting unit including a drive switch for starting the drive mechanism to drive the cooling mechanism the automatic drive admitting unit including a door open detecting switch for detecting that a door provided at a front body of the image forming apparatus has been opened thus outputting a drive admitting signal 9 A method of controlling a cooling mechanism of a fixing device of an image forming apparatus heated and fixed by which is an image forming medium transferred on which is a toner image formed on an image fixing body by an electrophotography process the fixing device including a fixing unit that presses and heats the image forming medium to be fixed by a pair of fixing rollers medium holding means provided at an outlet side of the fixing unit for holding the image forming medium on which an image has been fixed transferred and discharged by the fixing unit jam detecting means for detecting a jam in which the image forming medium has been caught between the fixing rollers and not moving and cooling means including a cooling mechanism for cooling the medium
4. fan 17 starts when the hinged door of the image forming apparatus 1 is detected to be opened and also the paper jamming is detected The difference between the third and the fourth embodi ment is that in the latter judgement on elapse of a set time is made in step ST10 before stopping the forced cooling fan 17 in step STS A control operation of the cooling mechanism in the fourth embodiment achieves double security by detection of the hinged door of the image forming apparatus 1 being opened and the paper jamming in the fixing device 10 The control operations of the cooling mechanism of the fixing device in the first to the fourth embodiments drives the cooling fan 17 to start by depressing the forced cooling button 18 However not limited to this the invention includes a modification to start a cooling operation just after detection 10 15 20 25 30 35 40 45 50 55 60 65 8 of a paper jamming and then stop the forced cooling fan 17 when a set time elapses FIG 8 shows a flow chart for explaining such a control operation of the cooling mechanism of the fixing device in the fifth embodiment In FIG 8 it is judged in step ST1 whether or not a paper jamming has been occurring in the fixing device 10 based on a detection signal from the detector 16 as a jam detecting means When there is a detection signal from the sensor 16 and it is judged that a paper jamming has been occurring in the fixing devic
5. fixing rollers and not moving and cooling means including a cooling mechanism for cooling the medium holding means and jamming image forming medium and a drive mechanism for driving the cooling mechanism the method comprising the steps of detecting a jam in which the image forming medium has been caught between the fixing rollers and not moving by the jam detecting means and admitting the drive mechanism to drive the cooling mechanism to cool the medium holding means and the jamming image forming medium located in the vicinity of the medium holding means wherein the step admitting the drive mechanism to drive includes the steps of generating a control signal based on the jam detected by the jam detecting means and automatic admission step of automatically driving the cooling means based on the control signal and wherein the automatic admission step includes the steps of detecting that a door provided at a front body of the image forming apparatus has been opened thus outputting a drive admitting signal driving the drive mechanism of the cooling means based on the output drive admitting signal and a manually operating step of manually operating a drive switch to stop the cooling mechanism kok o k k k
6. jamming sheet in the fixing device The fixing device consists of a fixing unit having fixing rollers and discharge guide unit for discharging a sheet after fixed by the fixing unit The cooling mechanism such as a cooling fan or a refrigerant cooling unit is provided at the discharge guide to cool the jamming sheet that has caused jamming only in the fixing unit and discharged therefrom Time for cooling the jamming sheet may be controlled by a user manual operation or for a predetermined period within a recovery allowable time so as not to cool the fixing rollers which would otherwise cause a long recovery time Or the cooling mechanism may start a cooling operation after detecting that a door provided at the front of the image forming apparatus has been opened for taking out the jamming sheet 16 Claims 8 Drawing Sheets MEDIUM HOLDING MEANS FIXING UNIT COOLING MEANS 17 JAM DRIVE DETECTING ADMITTING 18 MEANS MEANS US 6 374 063 B1 Sheet 1 of 8 Apr 16 2002 U S Patent SNVAW SNV3NW gi ONIL LINOY ONILOSLAG 9 3MYa Wyr JNI1009 SNVAW LINN ONIXIA ONIGIOH WNIG3aW el SS GI Old SS SS gt Sees anaes 450 733d S 1 UASU ae as a ey gt 4 dOTSARC eo a wes s I ooo 3SOdX3 i i ieee WE a I Lus a9YVHO Z 4 JIUVISI 0419313 La S S a LINA ONIGS 34 U S Patent Apr 16 2002 Sheet 2 of 8 US 6
7. of toner for example to the fixing rollers due to cooling The present invention thus achieves a cooling mechanism of a fixing device easy for post processing A method of controlling a cooling mechanism of a fixing device according to the second basic configuration of the present invention is a method of controlling a cooling mechanism of a fixing device of an image forming apparatus heated and fixed by which is an image forming medium transferred on which is a toner image formed on an image fixing body by an electrophotography process the fixing device including a fixing unit that presses and heats the image forming medium to be fixed by a pair of fixing rollers medium holding means provided at an outlet side of the fixing unit for holding the image forming medium on which an image has been fixed transferred and discharged by the fixing unit jam detecting means for detecting a jam in which the image forming medium has been caught between the fixing rollers and not moving and cooling means including a cooling mechanism for cooling the US 6 374 063 B1 3 medium holding means and jamming image forming medium and a drive mechanism for driving the cooling mechanism the method including the steps of detecting a jam in which the image forming medium has been caught between the fixing rollers and not moving by the jam detecting means and admitting the drive mechanism to drive the cooling mechanism to cool the medium holding means and t
8. sheet P as the image forming medium on which the image has been fixed a jam detecting means 16 to detect jamming in which the fixing roller 12 and 13 have been stopped due to the sheet P as the image forming means got caught in the gap between the rollers a cooling means 17 having a cooling mechanism for cooling the medium holding means 14 and the jamming sheet P as the image forming means and a drive mechanism for driving the cooling mechanism and a drive admitting means 18 to admit the driving mechanism to drive the cooling mechanism to cool the medium holding means 14 and the jamming image forming medium adjacent to the medium holding means The medium holding means 14 has a transfer discharge guide 15 for transferring and discharging the sheet P discharged from the fixing unit 11 Based on the basic structure shown in FIG 1 a structure of the cooling means 17 is disclosed with reference to FIGS 2 and 3 As illustrated in FIGS 2 and 3 the fixing device 10 is constituted by the fixing unit 11 and a discharge transfer guide 14 as the medium holding means The fixing means unit 11 contains the fixing rollers 12 and 13 A jam detecting sensor 16 as the jam detecting means is situated at the outlet side of the casing of the fixing unit 11 FIGS 2 and 3 illustrate the fixing unit 11 to which a sheet as the image forming medium is transferred from left to right in the drawings Such a sheet is often drawn as transfe
9. sheet that comes out after getting caught in the gap between the fixing roller 12 and 13 is shown When a user ceases depressing the force cooling button 18 it is judged in step ST4 that the button 18 is not depressed anymore and then the forced cooling fan 17 is stopped in step STS The manual operation described above avoids an unnec essary cooling operation to the heat rollers at the most Jamming in the fixing device 10 could occur in front of and after the fixing unit 11 however will not generate heat so much at the front side Moreover the sheet caught in the gap between the fixing rollers 12 and 13 is taken out in the transfer direction These are the reasons for providing the cooling fan 17 only at the downstream side of the fixing unit 11 The cooling fan 17 is controlled by the jam detecting sensor 16 and the switch 18 In other words it is driven only when the jam detecting sensor 16 detects jamming in the fixing device 10 and also the switch 18 is depressed Jamming occurring at places other than the fixing device 10 does not allow the cooling fan 17 to be driven even though a user unintentionally touches and depresses the switch 18 while opening the hinged door thus avoiding unnecessary cooling of the heat rollers 12 and 13 The cooling mechanism in the first embodiment shown in FIGS 1 to 4 performs cooling by a user manual operation except judgement on occurrence of jamming by the sensor 16 Not only this the presen
10. the drive mechanism for circulating the refrig erant of the refrigerant cooling unit the automatic driving admitting unit including the door open detecting switch for detecting that the door has been opened thus outputting the drive admitting signal to the drive mechanism 8 A fixing device of an image forming apparatus heated and fixed by which is an image forming medium transferred on which is a toner image formed on an image fixing body by an electrophotography process the fixing device com prising a fixing unit that presses and heats the image forming medium to be fixed by a pair of fixing rollers medium holding means provided at an outlet side of the fixing unit for holding the image forming medium on which an image has been fixed transferred and dis charged from the fixing unit jam detecting means for detecting a jam in which the image forming medium has been caught between the fixing rollers and not moving cooling means including a cooling mechanism for cooling the medium holding means and jamming image form ing medium and a drive mechanism for driving the cooling mechanism and drive admitting means for admitting the drive mechanism to drive the cooling mechanism to cool the medium holding means and the jamming image holding medium located in the vicinity of the medium holding means when the jamming image forming medium is detected by the jam detecting means wherein the drive admitting means includes an automatic
11. a United States Patent Todome US006374063B1 10 Patent No 45 Date of Patent US 6 374 063 BI Apr 16 2002 54 75 73 21 22 51 52 58 56 FEEDING FIKING DEVICE USED FOR IMAGE FORMING APPARATUS Inventor Tsuyoshi Todome Kawasaki JP Assignee Toshiba Tec Kabushiki Kaisha Tokyo JP Notice Subject to any disclaimer the term of this patent is extended or adjusted under 35 U S C 154 b by 0 days Appl No 09 671 154 Filed Sep 28 2000 nts ia G03G 15 00 G03G 15 20 IAA UA 399 18 399 22 399 92 Field of Search 399 18 21 22 399 33 92 124 81 271 273 272 References Cited U S PATENT DOCUMENTS 4 025 180 A 4 391 509 A 5 1977 Kurita et al 399 92 7 1983 Cavagnaro 399 18 pakia rufha pi tale 1 iELECTRO STATIC F 2 CHARGE __ I pantena j EXPOSE 3 l DEVELOP H 4 i ead I je KAA SSS ST l I I UNIT TRANSFER gt PEEL OFF FOREIGN PATENT DOCUMENTS JP 4 96077 3 1992 cited by examiner Primary Examiner Sophia S Chen 74 Attorney Agent or Firm Foley amp Lardner 57 ABSTRACT An image forming apparatus is provided with an electro static charging unit an exposure unit a developing unit a feeding unit a transfer unit a peeling off unit a fixing device and also a cooling mechanism used when taking out a
12. and driving the drive motor by means of the output drive admitting signal 15 The method of controlling the cooling mechanism of the fixing device according to claim 13 wherein the cooling means includes a refrigerant cooling unit as the cooling mechanism that is provided at a transfer plate that is included in the medium holding means for cooling the transfer plate by using a refrigerant and a refrigerant circu lating unit for circulating the refrigerant of the refrigerant cooling unit the automatic admission step including the steps of detecting that the door at the front body has been opened and outputting the drive admitting signal to the drive mechanism and driving the drive mechanism by means of the output drive admitting signal 16 A method of controlling a cooling mechanism of a fixing device of an image forming apparatus heated and fixed by which is an image forming medium transferred on which is a toner image formed on an image fixing body by 10 20 25 30 35 14 an electrophotography process the fixing device including a fixing unit that presses and heats the image forming medium to be fixed by a pair of fixing rollers medium holding means provided at an outlet side of the fixing unit for holding the image forming medium on which an image has been fixed transferred and discharged by the fixing unit jam detecting means for detecting a jam in which the image forming medium has been caught between the
13. ble and attachment of toner to the main mechanism of the image forming appara tus BRIEF DESCRIPTION OF DRAWINGS In the attached drawings FIG 1 is a block diagram showing a basic structure of a fixing device having a cooling mechanism as the first embodiment according to the present invention FIG 2 is a perspective view of a discharge guide unit having a fixing unit and a cooling mechanism of the fixing device according to the first embodiment FIG 3 is a sectional view of the discharge guide unit having the fixing unit and the cooling mechanism of the fixing device according to the first embodiment FIG 4 is a flow chart for explaining a cooling control operation of the fixing device according to the first embodi ment FIG 5 is a flow chart for explaining a cooling control operation of the fixing device according to the second embodiment FIG 6 is a flow chart for explaining a cooling control operation of the fixing device according to the third embodi ment FIG 7 is a flow chart for explaining a cooling control operation of the fixing device according to the fourth embodiment and FIG 8 is a flow chart for explaining a cooling control operation of the fixing device according to the fifth embodi ment DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Preferred embodiments according to the present invention will be disclosed with reference to the attached drawings Disclosed first is a fixing device having a c
14. chanism to drive the cooling mechanism to cool the medium holding means and the jamming image forming medium located in the vicinity of the medium holding means when the jamming image forming medium is detected by the jam detecting means 10 15 20 25 30 40 45 50 55 65 2 The drive admitting means may include a manual switch that is provided inside a door provided at a front body of the image forming apparatus for the cooling means to start by a user manual operation Or it may be an automatic drive admitting means by which a switch is turned on when the door provided at the front body is opened Moreover it is preferable that under combination of the manual switch and automatic control for example the cooling means is auto matically driven when the door is opened to cool at once the medium holding means and a jamming image forming medium that is located in the vicinity of the medium holding means and the cooling means is stopped by means of the manual switch when the medium holding means and the jamming image forming medium have been cooled enough For drive admission by a manual operation it is preferable that the drive mechanism of the cooling means is stopped when a user has not depressed the manual button anymore For automatic control it is preferable that after the driving mechanism of the cooling means has started to drive cooling is performed for a fixed period in which the drive mechanism has
15. continued driving until a predetermined period passes and the drive mechanism automatically stops when the predetermined period has passed The cooling means may in general be constituted by a cooling fan as a cooling mechanism and a motor as a drive mechanism for rotating the cooling fan The drive admitting means as a manual operating means thus can be an on off switch for a cooling fan driving motor The cooling means may be constituted as a unique configuration by a cooling mechanism in which a refrigerant pipe is provided along the bottom of a receiving plate of the medium holding means such as a discharge transfer guide and a drive mechanism for cooling by circulating a refrigerant through the refrig erant pipe of the cooling mechanism Configured as above when a paper jam occurs in the fixing unit a discharge transfer guide at the discharge side and an image forming medium such as a jamming sheet that has been discharged to the discharge side only are cooled without cooling the fixing unit itself Therefore a user can take out an image forming medium caught in the fixing unit with no uncomfortable feeling when performing a jam process Moreover the medium holding means such as a guide at the discharge side and an image forming medium such as a jamming sheet located in the vicinity of the medium holding means only are cooled without sending a cool wind or cool air to the fixing unit itself thus no occurrence of attachment
16. cting sensor 16 provided at the outlet side of the fixing rollers 12 and 13 like the first embodiment and the manual drive admitting unit 18 may include a driving switch for driving the refrigerant to circulate in the refrigerant cooling unit Moreover an automatic control may be performed with an open door detection switch as an automatic drive admit ting unit to detect an opened hinged door of the image forming apparatus 1 As disclosed above the cooling mechanism of the fixing device of the image forming apparatus according to the present invention includes a cooling fan or a refrigerant cooling mechanism as the cooling means attached to the transfer guide as the discharging unit provided at the outlet side of the fixing device to discharge an image forming medium The cooling fan or the refrigerant cooling mecha nism is driven while a user is depressing the forced cooling button The present invention when employing the cooling fan is provided with slits as a cooling window in the direction of transferring copied sheets at a portion of the transfer guide of the fixing devise at the rear side of which the cooling fan is attached The cooling window the slits provided in the direction of transferring copied sheets will not cause any problem on transfer Moreover each slit width of the cooling window is narrow enough so that a user cannot insert his or her finger into any slit while the cooling fan is rotating thus causing no inju
17. d of controlling the cooling mechanism of the fixing device according to claim 10 wherein the cooling means includes a refrigerant cooling unit as the cooling mechanism that is provided at a transfer plate that is included in the medium holding means for cooling the transfer plate by using a refrigerant and a refrigerant circu lating unit for circulating the refrigerant of the refrigerant cooling unit the step of driving by the user manual operation being performed by depressing the drive switch for driving circulation of the refrigerant cooling unit provided at an outlet side of the fixing rollers 13 A method of controlling a cooling mechanism of a fixing device of an image forming apparatus heated and fixed by which is an image forming medium transferred on which is a toner image formed on an image fixing body by an electrophotography process the fixing device including a fixing unit that presses and heats the image forming medium to be fixed by a pair of fixing rollers medium holding means provided at an outlet side of the fixing unit for holding the image forming medium on which an image has been fixed transferred and discharged by the fixing unit jam detecting means for detecting a jam in which the image forming medium has been caught between the fixing rollers and not moving and cooling means including a cooling mechanism for cooling the medium holding means and jamming image forming medium and a drive mechanism for driving the co
18. e 10 the forced cooling fan 17 is driven to start in step ST3 After that it is judged in step ST10 whether or not a set time has elapsed by a timer not shown for example If before elapsing the set time the process goes back to step ST3 to continue driving of the cooling fan 17 On the other hand if it is judged in step ST10 that the set time has elapsed the forced cooling fan 17 is stopped in step ST5 The present invention may perform a completely auto matic cooling control operation like the fifth embodiment with no manual switch operation when an object to be cooled by the cooling means 17 is not the heat rollers 12 but the top of a sheet caught in the gap between the rollers 12 and 13 at the outlet side of the fixing unit 11 The foregoing embodiments are disclosed with reference to FIGS 1 to 3 where the forced cooling fan 17 cools the sheet P as the image forming that has caused jamming so as to avoid the cooling the fixing rollers However not limited to this for example the present invention may employ the cooling means 17 constituted by a refrigerant cooling unit as a cooling mechanism provided under the transfer guide plate 15 configuring the medium holding means 14 that cools the transfer guide plate 15 by means of a refrigerant and a refrigerant circulating unit as a driving mechanism to circulate the refrigerant in the refrig erant cooling unit In this configuration the jam detecting means may include the jam dete
19. efrigerant of the refrigerant cooling unit provided at an outlet side of the fixing rollers In the method of controlling a cooling mechanism of a fixing device according to the second basic configuration the step of admitting the drive mechanism to drive may include the steps of generating a control signal based on the jam detected by the jam detecting means and automatic admission step of automatically driving the cooling means based on the control signal In this method the automatic admission step may include the steps of detecting that a door provided at a front body of the image forming apparatus has been opened thus outputting a drive admitting signal and driving the drive mechanism of the cooling means based on the output drive admitting signal In this case it is preferable that the cooling means includes a cooling fan as the cooling mechanism for sending a specific airflow in a direction of the medium holding means and a drive motor as the drive mechanism for rotating the cooling fan the automatic admission step including the steps of detecting that the door at the front body has been opened and outputting the drive admitting signal to the drive motor and driving the drive motor by means of the output drive admitting signal Furthermore in this case it is preferable that the cooling means includes a refrigerant cooling unit as the cooling mechanism that is provided at a transfer plate that is included in the medium holdin
20. g means for cooling the transfer plate by using a refrigerant and a refrigerant circu lating unit for circulating the refrigerant of the refrigerant cooling unit the automatic admission step including the steps of detecting that the door at the front body has been 10 15 20 25 30 35 40 45 50 55 60 65 4 opened and outputting the drive admitting signal to the drive mechanism and driving the drive mechanism by means of the output drive admitting signal Moreover in this method the automatic admission step may include the steps of detecting that a door provided at a front body of the image forming apparatus has been opened thus outputting a drive admitting signal driving the drive mechanism of the cooling means based on the output drive admitting signal and a manually operating step of manually operating a drive shut down switch to stop the cooling mechanism Accordingly the method of controlling a cooling mecha nism of a fixing device according to the second basic configuration of the present invention can basically effec tively drive the cooling mechanism of the fixing device according to the first basic configuration The method thus achieves effective cooling to the medium holding means at the outlet side of the fixing unit and the image forming medium transferred and discharged onto the medium hold ing means without cooling the fixing device itself and also without making a user uncomforta
21. he cooling mechanism to cool the medium holding means and the jamming image holding medium located in the vicinity of the medium holding means when the jamming image forming medium is detected by the jam detecting means wherein the drive admitting means includes an automatic drive admitting unit for automatically admitting the cooling means to be driven according to a predeter mined control signal after the jam has been detected in the jam detecting means and wherein the automatic drive admitting unit includes a door open detecting switch for detecting that a door provided at a front body of the image forming appara tus has been opened thus outputting a drive admitting signal 6 The fixing device according to claim 5 wherein the cooling means includes a cooling fan as the cooling mecha nism for sending a specific airflow in a direction of the medium holding means and a drive motor as the drive mechanism for rotating the cooling fan the automatic drive US 6 374 063 B1 11 admitting unit having the door open detecting switch for detecting that the door has been opened and outputting the drive admitting signal to the drive motor 7 The fixing device according to claim 5 wherein the cooling means includes a refrigerant cooling unit as the cooling mechanism that is provided at a transfer plate that is included in the medium holding means for cooling the transfer plate by using a refrigerant and a refrigerant circu lating unit as
22. he jamming image forming medium located in the vicinity of the medium holding means In the method of controlling a cooling mechanism of a fixing device according to the second basic configuration the step of admitting the drive mechanism to drive may include the step of driving the drive mechanism of the cooling means by a user manual operation In this method the step of driving by the user manual operation may be performed by depressing a drive switch for starting the drive mechanism to drive the cooling mecha nism In this case it is preferable that the cooling means includes a cooling fan as the cooling mechanism for sending a specific airflow in a direction of the medium holding means and a drive motor as the drive mechanism for rotating the cooling fan the step of driving by the user manual operation being performed by depressing a drive switch for starting the drive mechanism to drive the cooling fan pro vided in the vicinity of the fixing rollers Moreover in this case it is preferable that the cooling means includes a refrigerant cooling unit as the cooling mechanism that is provided at a transfer plate that is included in the medium holding means for cooling the transfer plate by using a refrigerant and a refrigerant circu lating unit for circulating the refrigerant of the refrigerant cooling unit the step of driving by the user manual operation being performed by depressing a drive switch for driving circulation of the r
23. holding means and jamming image 15 20 25 30 35 40 45 55 65 12 forming medium and a drive mechanism for driving the cooling mechanism the method comprising the steps of detecting a jam in which the image forming medium has been caught between the fixing rollers and not moving by the jam detecting means and admitting the drive mechanism to drive the cooling mechanism to cool the medium holding means and the jamming image forming medium located in the vicinity of the medium holding means wherein step of admitting the drive mechanism to drive includes the step of driving the drive mechanism of the cooling means by a user manual operation 10 The method of controlling the cooling mechanism of the fixing device according to claim 9 wherein the step of driving by the user manual operation is performed by depressing a drive switch for starting the drive mechanism to drive the cooling mechanism 11 The method of controlling the cooling mechanism of the fixing device according to claim 10 wherein the cooling means includes a cooling fan as the cooling mechanism for sending a specific airflow in a direction of the medium holding means and a drive motor as the drive mechanism for rotating the cooling fan the step of driving by the user manual operation being performed by depressing the drive switch for starting the drive mechanism to drive the cooling fan provided in the vicinity of the fixing rollers 12 The metho
24. ium on which image has been fixed transferred and discharged from the fixing unit jam detecting means for detecting a jam in which the image forming medium has been caught between the fixing rollers and not moving cooling means including a cooling mechanism for cooling the medium holding means and jamming image form ing medium and a drive mechanism for driving the cooling mechanism and drive admitting means for admitting the drive mechanism to drive the cooling mechanism to cool the medium holding means and the jamming image holding 10 15 20 25 30 3 nn 40 45 50 55 60 65 10 medium located in the vicinity of the medium holding means when the jamming image forming medium is detected by the jam detecting means wherein the drive admitting means includes a manual drive admitting unit for manually admitting the cooling means to be driven 2 The fixing device according to claim 1 wherein the manual drive admitting unit includes a drive switch for starting the drive mechanism to drive the cooling mecha nism 3 The fixing device according to claim 2 wherein the cooling means includes a cooling fan as the cooling mecha nism for sending a specific airflow in a direction of the medium holding means and a drive motor as the drive mechanism for rotating the cooling fan the manual drive admitting unit having the drive switch for driving the drive motor for the cooling fan 4 The fixing device acc
25. n could be obstructed because the control panel would be locked when a hinged door not shown of the apparatus 1 was opened for a jam process The switch 18 provided in the vicinity of the fixing device 10 is noticeable for a user for ease of use The cooling fan 17 is driven to cool a jamming paper and also the heat rollers 12 and 13 a little which makes long a copier recovery time after jamming In order to overcome such a problem a manual operation only is offered to the switch 18 In detail the switch 18 is not automatically turned on when a jamming occurs in the fixing device 10 whereas it is turned on when a user depresses it while a jamming paper is heated too much for a user to take out Moreover the cooling fan 17 is not driven for a set time but it is driven while the user is depressing the switch 18 FIG 4 shows a flow chart for explaining an operation of the cooling mechanism of the fixing device in the first embodiment It is judged whether or not jamming occurs in the fixing device 10 in step ST1 Judged next is whether or not a user depresses the switch 18 for the cooling fan 17 in step ST2 If the force cooling button 18 is judged as being depressed the forced cooling fan 17 is driven in step ST3 It is judged whether the forced cooling button 18 has been still depressed in step ST4 If it is still depressed the process goes back to step ST3 in which the forced cooling fan 17 is continuously driven to cool the top of the
26. oling mechanism the method comprising the steps of detecting a jam in which the image forming medium has been caught between the fixing rollers and not moving by the jam detecting means and admitting the drive mechanism to drive the cooling mechanism to cool the medium holding means and the jamming image forming medium located in the vicinity of the medium holding means wherein the step admitting the drive mechanism to drive includes the steps of generating a control signal based on the jam detected by the jam detecting means and automatic admission step of automatically driving the cooling means based on the control signal and US 6 374 063 B1 13 wherein the automatic admission step includes the steps of detecting that a door provided at a front body of the image forming apparatus has been opened thus outputting a drive admitting signal and driving the drive mechanism of the cooling means based on the output drive admitting signal 14 The method of controlling the cooling mechanism of the fixing device according to claim 13 wherein the cooling means includes a cooling fan as the cooling mechanism for sending a specific airflow in a direction of the medium holding means and a drive motor as the drive mechanism for rotating the cooling fan the automatic admission step including the steps of detecting that the door at the front body has been opened and outputting the drive admitting signal to the drive motor
27. ooling mecha nism a basic structure as the first embodiment according to the present invention with reference to FIGS 1 to 4 FIG 1 shows a block diagram of a fixing unit having a cooling mechanism as the first embodiment In FIG 1 an image forming apparatus 1 is provided with an electrostatic charging unit 2 to electrostatically charge a photo conductor drum an exposure unit 3 to expose the charge drum to a document pattern a developing unit 4 to US 6 374 063 B1 5 deposit a developer such as a toner on the pattern on the drum to form a toner image a feeding unit 5 to feed sheets of paper as an image forming medium a transfer unit 6 to transfer the toner image developed by the developing unit 4 to a sheet fed by the feeding unit 5 a peeing off unit 7 to peel off an excess toner from the transferred image and a fixing device 10 to fix the toner on the transferred image by means of heat and pressure The fixing device 10 is used for an image forming apparatus for forming a toner image on a fixing body by an electrophotography process and fixing the image on an image forming medium to which the toner image has been transferred by means of heat and pressure The fixing device 10 is provided with a fixing unit 11 having a pair of fixing rollers 12 and 13 for fixing the image on the image forming medium with heat and pressure a medium holding means 14 situated at the outlet side of the fixing unit 11 to transfer and discharge a
28. or a user to take it out Secondary a jamming sheet in the fixing device is taken out after it is fed in the transferring direction The cooling fan is controlled according to an output of the jam detection sensor furthermore it is driven by depressing a switch only for jamming in the fixing device In other words the cooling fan does not start for jamming outside the fixing device even though the switch is depressed This mechanism prevents unnecessary cooling of heat rollers The same advantages are given by the cooling fan that is configured by the refrigerant cooling mechanism as dis closed in the fifth embodiment The refrigerant cooling mechanism does not spatter heat soon caused by jamming because it is not an air cooling system like the cooling fan In other words the refrigerant cooling mechanism sends a cooled air directly to a jamming sheet via the guide plate 15 so that no cooled air is not sent toward the heat rollers 12 and 13 thus the rollers being prevented from cooling What is claimed is 1 A fixing device of an image forming apparatus heated and fixed by which is an image forming medium transferred on which is a toner image formed on an image fixing body by an electrophotography process the fixing device com prising a fixing unit that presses and heats the image forming medium to be fixed by a pair of fixing rollers medium holding means provided at an outlet side of the fixing unit for holding the image forming med
29. ording to claim 2 wherein the cooling means includes a refrigerant cooling unit as the cooling mechanism that is provided at a transfer plate that is included in the medium holding means for cooling the transfer plate by using a refrigerant and a refrigerant circu lating unit as the drive mechanism for circulating the refrig erant of the refrigerant cooling unit the manual driving admitting unit having the drive switch for driving circulation of the refrigerant of the refrigerant circulating unit provided at an outlet side of the fixing rollers 5 A fixing device of an image forming apparatus heated and fixed by which is an image forming medium transferred on which is a toner image formed on an image fixing body by an electrophotography process the fixing device com prising a fixing unit that presses and heats the image forming medium to be fixed by a pair of fixing rollers medium holding means provided at an outlet side of the fixing unit for holding the image forming medium on which an image has been fixed transferred and dis charged from the fixing unit jam detecting means for detecting a jam in which the image forming medium has been caught between the fixing rollers and not moving cooling means including a cooling mechanism for cooling the medium holding means and jamming image form ing medium and a drive mechanism for driving the cooling mechanism and drive admitting means for admitting the drive mechanism to drive t
30. perature decrease to the fixing unit while toner has been attached to the unit the cooled toner being hardly peeled off SUMMARY OF THE INVENTION A purpose of the present invention is to provide an image forming apparatus having a cooling mechanism that offers a jam process without annoying a user when performed to a fixing unit and without getting a fixing roller dirty by cooling only the outlet of the fixing unit and its peripheral In order to meet the purpose a fixing device of an image forming apparatus according to the first basic configuration of the present invention is an fixing device of an image forming apparatus heated and fixed by which is an image forming medium transferred on which is a toner image formed on an image fixing body by an electrophotography process the fixing device including a fixing unit that presses and heats the image forming medium to be fixed by a pair of fixing rollers medium holding means provided at an outlet side of the fixing unit for holding the image forming medium on which an image has been fixed transferred and discharged from the fixing unit jam detecting means for detecting a jam in which the image forming medium has been caught between the fixing rollers and not moving cooling means including a cooling mechanism for cooling the medium holding means and jamming image forming medium and a drive mechanism for driving the cooling mechanism and drive admitting means for admitting the drive me
31. r printing data transferred from an image data supplying apparatus such as a personal computer and a digital camera on plane papers or OHP sheets Particularly this invention relates to a fixing device having a cooling mechanism for cooling a medium to be taken out when a paper jam occurs while fixing a color material deposited on the medium An image forming apparatus is generally equipped with an optical unit an exposure unit a developing unit a paper feeding unit a transfer unit a fixing unit and so on The paper feeding transfer and fixing units would suffer a paper jam in which any of the units is jammed by sheets of paper as an image forming medium on which an image is formed A paper jam could occur anywhere in the units to which sheets are transferred When a paper jam occurs in the fixing unit that has been generating a high heat a user has to open a hinged door of an image forming apparatus to find a unit that has been suffering a paper jam for taking out the jamming sheets a jam process Such a jam process annoys a user particularly when it occurs to the fixing unit because jamming papers are often heated when a hinged door of an image forming apparatus is opened due to the facts that a paper jam occurs right after a fixing process or a heat generating fixing unit is very close to the papers Rapid cooling to the fixing unit for taking out the jamming papers when a paper jam occurs around the fixing unit could cause tem
32. rred from right to left for a usual image forming apparatus The fixing unit is however drawn in FIGS 2 and 3 in this specification such that a sheet is transferred in the same direction as that shown in FIG 1 to match the state with each other The direction illustrated in these drawings is decided in this specification for convenience The arrows shown in FIGS 2 and 3 represent the transferring and discharging direction for the sheet as image forming medium Attached under the discharge transfer guide 14 at the fixing unit 11 side is a cooling fan 17 as the cooling means On the guide 14 at the part along which the sheet discharged from the fixing unit 11 is guided and where the cooling fan 17 is attached slits are formed in the direction of the arrows in FIGS 2 and 3 in which the sheet is transferred as the image forming medium The slits constitute an opening 19 for cooling The slits are formed in the direction of sheet transfer so that they will not obstruct the sheet transfer Moreover each slit width is narrow enough so that an operator cannot insert his or her finger into any slit while the cooling fan 17 is rotating to secure safety 5 10 15 20 25 30 35 40 45 50 55 60 65 6 The cooling fan 17 has a switch 18 provided in the vicinity of the fixing device 10 inside the image forming apparatus 1 not on a control panel not shown If it were provided on the control panel a regular operatio
33. ry The switch for the cooling fan is provided not on the control panel but in vicinity of the fixing device in the image US 6 374 063 B1 9 forming apparatus This is because the control panel would be locked when the door is opened for jam processing if such a switch is provided on the control panel and also the switch provided at a place such as in vicinity of the fixing device is noticeable for a user thus being user friendly Cooled by the cooling fan is not only jamming sheets but also the heat rollers which causes lengthening of a recovery time for a copier after jamming process To overcome such a drawback the present invention is configured such that the cooling fan is not automatically driven whenever jamming occurs in the fixing device but it is driven only when a user depresses a switch who cannot take out a heated sheet or do not like to take out such a heated sheet Moreover cooling is not performed for a set time in other words the cooling fan is driven while a user is depressing a switch This arrangement achieves driving of the cooling fan only for a period required by a user thus minimizing unnecessary cooling of heat rollers The cooling fan is provided only the outlet side of the fixing device for the following reasons Firstly jamming would occur at any places before and after the fixing device however its occurrence before a sheet is taken into the fixing device mostly generates heat not so much f
34. t invention offers a complete automatic cooling operation FIG 5 shows a flow chart for explaining an operation of the cooling mechanism in the second embodiment The basic hardware for the second embodiment is the same as that for the first embodiment shown in FIGS 1 to 3 US 6 374 063 B1 7 In the second embodiment an automatic cooling opera tion is performed for a set time when the forced cooling button 18 is depressed It is judged whether or not jamming occurs in the fixing device 10 in step ST1 by means of a detection signal from the jam detecting sensor 16 If jamming is occurring judged next is whether or not a user depresses the forced cooling button 18 in step ST2 If it is depressed the cooling fan 17 starts in step ST3 It is judged whether a set time has elapsed in step ST10 If not elapsed the process goes back to step ST3 to continuously drive the cooling fan 17 whereas if elapsed the process goes to step ST5 to stop the cooling fan 17 The second embodiment shown in FIG 5 offers an automatic cooling operation in which once the switch button 18 is depressed the forced cooling fan 17 is driven for a set time by a timer to a jamming paper with no necessity of continuous switch depressing thus avoiding a complex operation Care must be taken for taking out the jamming sheet P got caught between the fixing rollers however the second embodiment requires no continuous depressing of the forced cooling button 18
Download Pdf Manuals
Related Search