CA1071694A - Dry hot roll fusher having early fusing nip closure - Google Patents
Dry hot roll fusher having early fusing nip closureInfo
- Publication number
- CA1071694A CA1071694A CA250,131A CA250131A CA1071694A CA 1071694 A CA1071694 A CA 1071694A CA 250131 A CA250131 A CA 250131A CA 1071694 A CA1071694 A CA 1071694A
- Authority
- CA
- Canada
- Prior art keywords
- hot roll
- fusing
- temperature
- roll
- sheet
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G15/00—Apparatus for electrographic processes using a charge pattern
- G03G15/20—Apparatus for electrographic processes using a charge pattern for fixing, e.g. by using heat
- G03G15/2003—Apparatus for electrographic processes using a charge pattern for fixing, e.g. by using heat using heat
- G03G15/2014—Apparatus for electrographic processes using a charge pattern for fixing, e.g. by using heat using heat using contact heat
- G03G15/2017—Structural details of the fixing unit in general, e.g. cooling means, heat shielding means
- G03G15/2032—Retractable heating or pressure unit
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G2215/00—Apparatus for electrophotographic processes
- G03G2215/20—Details of the fixing device or porcess
Abstract
DRY HOT ROLL FUSER HAVING EARLY FUSING NIP CLOSURE
Abstract A dry release hot roll fuser wherein the hot roll is internally heated, the surface of the hot roll is de-Formable, and a rigid backup roll is force biased into the hot roll to form an axial depression in the hot roll, which depression comprises the fusing nip. The fusing nip is closed prior to the arrival of a sheet to be fused. The early closing time interval is such as to cause the hot roll to complete at least one revolu-tion against the cooler backup roll, prior to arrival of the first sheet to be fused.
In the standby mode, the fusing nip is open, and the hot roll temperature is controlled to be at a temperature higher than the desired fusing temperature. This higher temperature is desirable since it is known that the thick deformable surface on the hot roll will cause the fusing temperature to droop during fusing. Since the hot roll's surface is relatively thick, and formed of a heat insulator, such as silicone rubber, the droop which occurs is a result of the cooling effect of the first sheets to be fused.
After the early closing interval, the hot roll's fusing temperature has drooped to the vicinity of the optimum fusing temperature and the automatic temperature control system thereafter supplies just enough additional internal heat energy to offset the cooling effect of the sheets. The probability of the first sheet sticking to the hot roll has been reduced as a result of this roll early closing.
To accommodate the high standby temperature, the fusing nip is closed early--i.e. before a sheet arrives at the fusing nip. The time period of this early closure is critical, and has been found to be such as will produce at least one revolution of the hot roll prior to the arrival of a sheet to be fused. It has been found that this early closing of the fusing nip causes a rapid droop in the fusing nip temperature to approximately the optimum fusing temperature prior to arrival of the first sheet to be fused, and thereafter the temperature control system maintains the optimum temperature. Thus, wrap of the sheets about the hot roll is minimized.
Abstract A dry release hot roll fuser wherein the hot roll is internally heated, the surface of the hot roll is de-Formable, and a rigid backup roll is force biased into the hot roll to form an axial depression in the hot roll, which depression comprises the fusing nip. The fusing nip is closed prior to the arrival of a sheet to be fused. The early closing time interval is such as to cause the hot roll to complete at least one revolu-tion against the cooler backup roll, prior to arrival of the first sheet to be fused.
In the standby mode, the fusing nip is open, and the hot roll temperature is controlled to be at a temperature higher than the desired fusing temperature. This higher temperature is desirable since it is known that the thick deformable surface on the hot roll will cause the fusing temperature to droop during fusing. Since the hot roll's surface is relatively thick, and formed of a heat insulator, such as silicone rubber, the droop which occurs is a result of the cooling effect of the first sheets to be fused.
After the early closing interval, the hot roll's fusing temperature has drooped to the vicinity of the optimum fusing temperature and the automatic temperature control system thereafter supplies just enough additional internal heat energy to offset the cooling effect of the sheets. The probability of the first sheet sticking to the hot roll has been reduced as a result of this roll early closing.
To accommodate the high standby temperature, the fusing nip is closed early--i.e. before a sheet arrives at the fusing nip. The time period of this early closure is critical, and has been found to be such as will produce at least one revolution of the hot roll prior to the arrival of a sheet to be fused. It has been found that this early closing of the fusing nip causes a rapid droop in the fusing nip temperature to approximately the optimum fusing temperature prior to arrival of the first sheet to be fused, and thereafter the temperature control system maintains the optimum temperature. Thus, wrap of the sheets about the hot roll is minimized.
Description
18 Background and Summary of the Invention 19 The present invention relates to the xero-graphic process step of fusing toner to support material 21 by a dry release hot roll contact fuser.
22 In the xerographic process a toned visual 23 image is transferred to a copy medium, for example 24 a sheet of copy paper, at a transfer station. The toner is usually a pigmented thermoplastic resin.
26 ,The individual toner particles'are formulated such 27 that they will soften under heat. When soft, they 28 firmly stick to the surface of the copy pap2r. In BO9'75010 -2-' ' . _ .
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1 order to fuse the toned copy paper it is nece~sary
22 In the xerographic process a toned visual 23 image is transferred to a copy medium, for example 24 a sheet of copy paper, at a transfer station. The toner is usually a pigmented thermoplastic resin.
26 ,The individual toner particles'are formulated such 27 that they will soften under heat. When soft, they 28 firmly stick to the surface of the copy pap2r. In BO9'75010 -2-' ' . _ .
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1 order to fuse the toned copy paper it is nece~sary
2 to heat the toner to a relatively hiyh temperature,
3 usually in excess of 200 F. One method of so heating
4 the toner is by a hot roll contact fuser. The hot roll fuser operates to pass the toned copy sheet 6 through a fusing nip formed by a heated and driyen 7 fuser roll, and a backup roll. This step o contact 8 fusing usually produces a tendency for th~ toned 9 side of the copy paper to adhere to the surface of the hot roll. If the sheet o~ copy paper should 11 adhere to the hot roll, a-paper jam or roll~wrap 12 occurs.
13 Prior hot roll fusers may be of the WQt 14 release type wherein a release liquid such as sil$cone oil is supplied to the fusing nip to enhance release - 16 of the toned paper sheet from the fuser rolls. Such 17 hot roll fusers generally use a thick, soft elastomer 18 coating on the metal core of the backup roll and 19 a thin elastomer coating on the metal core of the hot roll. ~len the two rolls are force-biased toward 21 each other, to form a fusing nip, an axial depression, 22 also called a footprint, i5 formed in the backup -23 roll. The prior art has been constructed in this 24 manner to enable the use of a thin elastomer coating on the hot roll, thereby preventing exc~ssive hot 26 roll surface temperature excursion between the standby 27 condition and the ~using condition. The use of silicone ~ 28 oil i5 costly, and tends to coa-t the paper with oil.
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~7~94 1 It has been proposed that the thick deformable elastomer coating be placed on the hot roll, and 3 that the backup roll be provided with a ~igid surfac~, 4 such ~l~t the closing of the fusing nip ~esults in a footprin-t deformation into the hot roll's thick, 6 soft coating. An advantage of such a structure is 7 that the nip configuration of the deformable hot 8 roll provides a contour which is shaped such as 9 to aid in the release of the toned side o~ the sheet from the hot roll. The shape of this nip is such 11 that the paper is literally pushed away from the 12 hot roll upon exit from the nip, thereby tending 13 to overcome the tendency of the hot toned sheet to 14 stick to the hot roll's surface.
lS With this type of fuser, it is necessary 16 that the hot roll's metal core be maintained at 17 a temperature which is higher than the optimum fusing 18 temperature. This is true since a copy run involving 19 a number of sheets rèquires that sufficient heat be supplied through khis relatively thick heat insulator - 21 to prevent the fusing nip temperature from drooping 22 to a temperature below the optimum fusing temperature.
23 However, the use of the hot roll's thick elastomer 24 coating allows the hot roll's fusing surface to achi~ve unduly high temperatures, substantially above the 26 optirnum fusing temperature, when in a standby~condition, 27 due to the ~act that this thick elastomer coating, 28 ~which is a good heat insulator~ approache~ the tempera-29 ture o~ the hot roll's metallic core.
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1 The fusing nip temperature is critical.
2 If the temperature is too low, the toner will not 3 fuse, whereas too high a fusing temperature tends 4 to cause the toner side of the sheet to stick to the hot roll. This narrow temperature window pla~es 6 many restrictions on the construction of a hot roll 7 fuser.
8 The present invention successfully overcomes 9 these problems in,a dry release hot roll fuser who~e hot roll is coated with a thick deformable elastomer 11 by providing early closure of the hot roll 1 5 fu~ing 12 nip. Thus, even though the external surface of the 13 elastomer coating may elevate to an unduly high tempera-14 ture during a,standby period, the early closure of the fusing nip causes this external surface to be 16 cooled, much as it would be cooled by the ~using 17 of sheets. By the time the first sheet to be fused 18 arrives at the fusing nip, the temperature at the 19 fusing nip has lowered to the vicinity of the optimum fusing temperature and adequate fusing occurs without .
21 relea~se failure.
22 As a further feature of the present invention,~
23 the rigid backup roll is constructed and arranged 24 to be generally equal to the cooling ef~ect of a-sheet to be fused.
26 ' The foregoing,and o~her features and advanta-27 ges o~ the,invention will be apparent from the follo~ing 28 more particular description of a preferred embodiment .
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~C~73~694 1 of the invention, as illustrated in the acco~panying 2 drawing.
3 Brief Description of the Drawing 4 FIGURE 1 is a schematic view of a xerogr~phic copying apparatus incorporating the present invention;
6 FIGURE 2 is a side view of the fu~ing nip 7 portion of FIG~RE l's hot dry release roll fuser; ~nd 8 FIGURE 3 is a time-temperature graph which 9- plots the fusing nip temperature profile achieved by operation of the present invention~ For comparlson, 11 the broken line curve of FIGURE 3 plots an exemplary 12 fusing nip temperature profile wherein the early 13 roll closing feature of the present invention is 14- not used.
Description of the Preferred Embodi~ent 16 FIGURE 1 is a schematic view of a xerographic 17 copying apparatus incorporating thé present invention.
18 In this device a scanning mirror system 10 and a 19 moving lens 11 move in synchronism with the rotation of photoconductor drum 12 to place a latent image 21 of an original document 13 onto the drum's surface.
22 As is well known, prior to imaging at 14 the drum 23 is charged by corona 15. After imaging, the drum's 24 latent image is developed by magnetic brush d~veloper 16. Thereafter the drum's toned visible image is 26 transferred to a sheet of copy paper at transfer 27 station 17 by operation of transfer corona 18. Sheet 28 detach means l9 operates to cause the now-toned sheet , .
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to leave the surface of the drum and to follow sheet path 20, adjacent vacuum conveyor 21 on ;ts way to dry release hot roll fuser assembly 22.
After fusing, the finished copy sheet follows sheet path 23 and is deposited in tray 24. After transfer, the drum is cleaned as it passes cleanin~
station 25.
The apparatus o~ FIGURE 1 includes a copy sheet supply bin 26.
This supply bin includes a bidirectionally movable elevator which supports the bottom sheet of the stack. While this structure is well known to those of skill in the art, an exemplary structure is described in the IBM
TECHNICAL DISCLOSURE BULLETIN of August 1974, at pages 670 and 671. The bin is operable to feed the top sheet of the stack to sheet discharge path 27. This sheet then travels down sheet path 28 to be momentarily stopped at gate 29. When the leading edge of the drum's toned image arrives at the vicinity of the gate, the gate is opened to allow the sheet to progress into transfer station 17 in exact registry with the drum's image. An exemplary means of picking the top sheet from the bin is described in the IBM TECHNICAL DISCLOSURE BULLETIN of February 1974, at pages 2966 and 2967.
The apparatus of FIGURE 1 includes control logic 30 which is operable to program or time the operation of the various mechanisms within the copying appanatus of FIGURE 1.
.....
_r Registered Trade Mark 9~
1 Tlle present inventiorl provides an lmproved 2 dry release hot roll fuser to inhibit the toned side 3 of the copy sheet from adhering to hot roll 31, as 4 this sheet is pressed into ~he hot roll by backup roll 32, ; 6 The fusing nip formed by rolls 31 and 32 7 is preferably opened and closed by control loglc 8 30, as thls logic is controlled by a drum position - 9 sensing means, not shown, which responds to the posi-tion of drum 12 and effects opening and closing of 11 the nip by means of a control system, not shown.
12 An exemplary mechanism for effecting the opening 13 and closing of this nip is shown in the IBM TECHNICAL
:14 DISCLOSURE BULLETIN of May 1973, at page 3644.
With the exception of the early closing .
16 feature of the present lnvention, it is desirable 17 that the fusing nip be closed only.when paper is 18 between the rolls. Thus, it is desirable to open 19 the fusing nip during the inter-sheet gap~ which ; ~ 20 may exist between adjacent sheets to be fused, and , 21 to close the nip when the next sheet.arrives. In 22 the alternative, the sheet velocity may be reduced 23 in the fuser, to ellminate this inter-sheet gap, , - , 24 in the manner described in U. S. Patent 3,794,417, issued to J. A. Machmer.
26 FIGURE 2 discloses FIGURE l's hot roll 27 fuser 22 in detail. Hot roll 31 is an aluminum cylinder 28 having a thick, de~ormable silicone elastom~r outer , . .
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1 layer 33. A pair of insulating end walls are fitt~d 2 into cylinder 31 at each end and support bearings 3 which, in turn, support the cylinder for rotation 4 about i-ts longitudinal axis. A conventional tungst~n filament infrared heating lamp is located along this 6 axis. A reflective end plate may be carried within 7 the cylinder at each end to improve the axial uniformity 8 of heat reception by the cylinder from the lamp.
9 The inner surface of cylinder 31 may be colored black to improve its radiant energy absorption characteristic.
11 Backup roll 32 is constructed and arrangéd 12 to simulate the cooling effect of the sheets to be 13 fused. Specifically, this roll may be a polished 14 cromlum plated steel roll, or may be made of a tubular aluminum extruslon having a relatively heavy cylindrical 16 wall section ànd, for example, a smooth outer surface 17 of polytetrafluoroethelene.
18 As shown in FIGURE 2, the deformable outer 19 surface 33 layer o~ heated roll 31 is indented by backup roll 32 to produce at the exit of fusing nip 21 33 a curvature tending to separate paper copy she~t 22 34 from the surface of heated roll 50.
23 The thick, deformabIe outer surface 33 24 of the hot roll is preferably an elastomeric heat insulating layer. An example of such a material 26 is a ~ilicone elastomer,,such as the silicone rubber 27 material manufactured and sold by General Electric 28 Corporation, deslgnated as RTV-60. ~ preferred dry , .
.
~7~L6'~4 l release hot roll fuser is described in United States 2 Patent 3, 848, 305, issued to P. D. Jachimiak.
3 The hot roll's metal tube or core i5 main-4 tained at a controlled temperature by a temperature sensing and control means, not shown. An exemplary 6 means for accomplishing this result is described 7 in the IBM TECHNICAL DISCLOSURE BULLETIN of October 8 1972, at page 1587. A temperature sensor, not shown, 9 operates to sense the temperature of the outer surface of this metal tube. Since layer 33 is a good heat - ll insulator, the temperature of this outer surface 12 is maintained above the optimum fusing temper~ture 13 during a standby period--i.e. when the fusing nip .
14 is open.
With reference to FIGURE 3, an exemplary 16 control temperatuxe ls seen to be 375 F. Thus, 17 during standby periods the outer surface of layer 18 33 achieves this high temperature. At time zero 19 control logic 30 of FIGURF. 1 is enabled to begin a copy run. The temperature profile plotted in FIGURE
21 3 assures a standby period long enough fox the outer 22 surface of layer 33 to assume the same temperature 23 aS the hot roll's inner tube, namely 375. As the 24 copy process continues, and at approximately 1.5 seconds into the proces~, control logic 30 operates 26 to close the fusing nip. This is indicated a~ point 27 35 on the curve. From this time until approximately ~8 the 2.5-second time the hot roll and the backup roll .
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1 are in fusing engagement with no sheet interposed 2 be~ween them. As a result of the cooling effect 3 provided by the backup roll, the fusing temperature 4. drops rapidly, following curve 36. At ~7 the first sheet arrives to be fused, and the temperature of 6 the fusing nip has now been cooled approximately 7 to the optimum fusing temperature, namely 340.
8 The backup roll used in FIGURE 3 has a 9 cooling effect somewhat greater than the sheets to be fused. A preferred feature is that the backup .11 roll must cool the hot roll at least as well as sheets 12 to be fused.
13 For comparison, dotted line 38 plot~ the 14 fusing temperature of a hot roll, having a thick.
deformable elastomeric heat insulating coating when 16 early closure o~ the fusing nip is not provided.
17 In this case, at least the first sheet is subjected 18 to an average fusing temperature o about 370, and 19 sticking to the hot roll is likely.to occur.
Preferably, the hot roll and backup roll 21 may be constructed to have diameters in the range 22 of from 1 to 5 inchesi the deformable elastomeric .
23 heat insulating coating on the hot roll may have 24 a-thickness in the range of from .02 to .06 inch;.
and the surface velocity of the rolls is such as 26. to achieve a sheet velocity, through the fusing nip, 27 of from 10 to 30 inches per second. As a result, 28 the fusing nip preferably has a width in the range , . . .
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~7~694 1 of from .1 to .4 inch, measured in the direction 2 of roll rotation.
3 While the invention has been particularly 4 shown and described with reference to a preferred embodiment thereof, it will be understood by those 6 skilled ln the art that various changes in form and 7 details may be made therein without departing from 8 the spirit and scope of the invention.
9 What is claimed is:
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13 Prior hot roll fusers may be of the WQt 14 release type wherein a release liquid such as sil$cone oil is supplied to the fusing nip to enhance release - 16 of the toned paper sheet from the fuser rolls. Such 17 hot roll fusers generally use a thick, soft elastomer 18 coating on the metal core of the backup roll and 19 a thin elastomer coating on the metal core of the hot roll. ~len the two rolls are force-biased toward 21 each other, to form a fusing nip, an axial depression, 22 also called a footprint, i5 formed in the backup -23 roll. The prior art has been constructed in this 24 manner to enable the use of a thin elastomer coating on the hot roll, thereby preventing exc~ssive hot 26 roll surface temperature excursion between the standby 27 condition and the ~using condition. The use of silicone ~ 28 oil i5 costly, and tends to coa-t the paper with oil.
,........ , , , ' .. ; . . , - . .
~7~94 1 It has been proposed that the thick deformable elastomer coating be placed on the hot roll, and 3 that the backup roll be provided with a ~igid surfac~, 4 such ~l~t the closing of the fusing nip ~esults in a footprin-t deformation into the hot roll's thick, 6 soft coating. An advantage of such a structure is 7 that the nip configuration of the deformable hot 8 roll provides a contour which is shaped such as 9 to aid in the release of the toned side o~ the sheet from the hot roll. The shape of this nip is such 11 that the paper is literally pushed away from the 12 hot roll upon exit from the nip, thereby tending 13 to overcome the tendency of the hot toned sheet to 14 stick to the hot roll's surface.
lS With this type of fuser, it is necessary 16 that the hot roll's metal core be maintained at 17 a temperature which is higher than the optimum fusing 18 temperature. This is true since a copy run involving 19 a number of sheets rèquires that sufficient heat be supplied through khis relatively thick heat insulator - 21 to prevent the fusing nip temperature from drooping 22 to a temperature below the optimum fusing temperature.
23 However, the use of the hot roll's thick elastomer 24 coating allows the hot roll's fusing surface to achi~ve unduly high temperatures, substantially above the 26 optirnum fusing temperature, when in a standby~condition, 27 due to the ~act that this thick elastomer coating, 28 ~which is a good heat insulator~ approache~ the tempera-29 ture o~ the hot roll's metallic core.
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1 The fusing nip temperature is critical.
2 If the temperature is too low, the toner will not 3 fuse, whereas too high a fusing temperature tends 4 to cause the toner side of the sheet to stick to the hot roll. This narrow temperature window pla~es 6 many restrictions on the construction of a hot roll 7 fuser.
8 The present invention successfully overcomes 9 these problems in,a dry release hot roll fuser who~e hot roll is coated with a thick deformable elastomer 11 by providing early closure of the hot roll 1 5 fu~ing 12 nip. Thus, even though the external surface of the 13 elastomer coating may elevate to an unduly high tempera-14 ture during a,standby period, the early closure of the fusing nip causes this external surface to be 16 cooled, much as it would be cooled by the ~using 17 of sheets. By the time the first sheet to be fused 18 arrives at the fusing nip, the temperature at the 19 fusing nip has lowered to the vicinity of the optimum fusing temperature and adequate fusing occurs without .
21 relea~se failure.
22 As a further feature of the present invention,~
23 the rigid backup roll is constructed and arranged 24 to be generally equal to the cooling ef~ect of a-sheet to be fused.
26 ' The foregoing,and o~her features and advanta-27 ges o~ the,invention will be apparent from the follo~ing 28 more particular description of a preferred embodiment .
BO9750'10 -S-.
.
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. ~, . . .
~C~73~694 1 of the invention, as illustrated in the acco~panying 2 drawing.
3 Brief Description of the Drawing 4 FIGURE 1 is a schematic view of a xerogr~phic copying apparatus incorporating the present invention;
6 FIGURE 2 is a side view of the fu~ing nip 7 portion of FIG~RE l's hot dry release roll fuser; ~nd 8 FIGURE 3 is a time-temperature graph which 9- plots the fusing nip temperature profile achieved by operation of the present invention~ For comparlson, 11 the broken line curve of FIGURE 3 plots an exemplary 12 fusing nip temperature profile wherein the early 13 roll closing feature of the present invention is 14- not used.
Description of the Preferred Embodi~ent 16 FIGURE 1 is a schematic view of a xerographic 17 copying apparatus incorporating thé present invention.
18 In this device a scanning mirror system 10 and a 19 moving lens 11 move in synchronism with the rotation of photoconductor drum 12 to place a latent image 21 of an original document 13 onto the drum's surface.
22 As is well known, prior to imaging at 14 the drum 23 is charged by corona 15. After imaging, the drum's 24 latent image is developed by magnetic brush d~veloper 16. Thereafter the drum's toned visible image is 26 transferred to a sheet of copy paper at transfer 27 station 17 by operation of transfer corona 18. Sheet 28 detach means l9 operates to cause the now-toned sheet , .
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to leave the surface of the drum and to follow sheet path 20, adjacent vacuum conveyor 21 on ;ts way to dry release hot roll fuser assembly 22.
After fusing, the finished copy sheet follows sheet path 23 and is deposited in tray 24. After transfer, the drum is cleaned as it passes cleanin~
station 25.
The apparatus o~ FIGURE 1 includes a copy sheet supply bin 26.
This supply bin includes a bidirectionally movable elevator which supports the bottom sheet of the stack. While this structure is well known to those of skill in the art, an exemplary structure is described in the IBM
TECHNICAL DISCLOSURE BULLETIN of August 1974, at pages 670 and 671. The bin is operable to feed the top sheet of the stack to sheet discharge path 27. This sheet then travels down sheet path 28 to be momentarily stopped at gate 29. When the leading edge of the drum's toned image arrives at the vicinity of the gate, the gate is opened to allow the sheet to progress into transfer station 17 in exact registry with the drum's image. An exemplary means of picking the top sheet from the bin is described in the IBM TECHNICAL DISCLOSURE BULLETIN of February 1974, at pages 2966 and 2967.
The apparatus of FIGURE 1 includes control logic 30 which is operable to program or time the operation of the various mechanisms within the copying appanatus of FIGURE 1.
.....
_r Registered Trade Mark 9~
1 Tlle present inventiorl provides an lmproved 2 dry release hot roll fuser to inhibit the toned side 3 of the copy sheet from adhering to hot roll 31, as 4 this sheet is pressed into ~he hot roll by backup roll 32, ; 6 The fusing nip formed by rolls 31 and 32 7 is preferably opened and closed by control loglc 8 30, as thls logic is controlled by a drum position - 9 sensing means, not shown, which responds to the posi-tion of drum 12 and effects opening and closing of 11 the nip by means of a control system, not shown.
12 An exemplary mechanism for effecting the opening 13 and closing of this nip is shown in the IBM TECHNICAL
:14 DISCLOSURE BULLETIN of May 1973, at page 3644.
With the exception of the early closing .
16 feature of the present lnvention, it is desirable 17 that the fusing nip be closed only.when paper is 18 between the rolls. Thus, it is desirable to open 19 the fusing nip during the inter-sheet gap~ which ; ~ 20 may exist between adjacent sheets to be fused, and , 21 to close the nip when the next sheet.arrives. In 22 the alternative, the sheet velocity may be reduced 23 in the fuser, to ellminate this inter-sheet gap, , - , 24 in the manner described in U. S. Patent 3,794,417, issued to J. A. Machmer.
26 FIGURE 2 discloses FIGURE l's hot roll 27 fuser 22 in detail. Hot roll 31 is an aluminum cylinder 28 having a thick, de~ormable silicone elastom~r outer , . .
~ BO975010 ~8-.
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1 layer 33. A pair of insulating end walls are fitt~d 2 into cylinder 31 at each end and support bearings 3 which, in turn, support the cylinder for rotation 4 about i-ts longitudinal axis. A conventional tungst~n filament infrared heating lamp is located along this 6 axis. A reflective end plate may be carried within 7 the cylinder at each end to improve the axial uniformity 8 of heat reception by the cylinder from the lamp.
9 The inner surface of cylinder 31 may be colored black to improve its radiant energy absorption characteristic.
11 Backup roll 32 is constructed and arrangéd 12 to simulate the cooling effect of the sheets to be 13 fused. Specifically, this roll may be a polished 14 cromlum plated steel roll, or may be made of a tubular aluminum extruslon having a relatively heavy cylindrical 16 wall section ànd, for example, a smooth outer surface 17 of polytetrafluoroethelene.
18 As shown in FIGURE 2, the deformable outer 19 surface 33 layer o~ heated roll 31 is indented by backup roll 32 to produce at the exit of fusing nip 21 33 a curvature tending to separate paper copy she~t 22 34 from the surface of heated roll 50.
23 The thick, deformabIe outer surface 33 24 of the hot roll is preferably an elastomeric heat insulating layer. An example of such a material 26 is a ~ilicone elastomer,,such as the silicone rubber 27 material manufactured and sold by General Electric 28 Corporation, deslgnated as RTV-60. ~ preferred dry , .
.
~7~L6'~4 l release hot roll fuser is described in United States 2 Patent 3, 848, 305, issued to P. D. Jachimiak.
3 The hot roll's metal tube or core i5 main-4 tained at a controlled temperature by a temperature sensing and control means, not shown. An exemplary 6 means for accomplishing this result is described 7 in the IBM TECHNICAL DISCLOSURE BULLETIN of October 8 1972, at page 1587. A temperature sensor, not shown, 9 operates to sense the temperature of the outer surface of this metal tube. Since layer 33 is a good heat - ll insulator, the temperature of this outer surface 12 is maintained above the optimum fusing temper~ture 13 during a standby period--i.e. when the fusing nip .
14 is open.
With reference to FIGURE 3, an exemplary 16 control temperatuxe ls seen to be 375 F. Thus, 17 during standby periods the outer surface of layer 18 33 achieves this high temperature. At time zero 19 control logic 30 of FIGURF. 1 is enabled to begin a copy run. The temperature profile plotted in FIGURE
21 3 assures a standby period long enough fox the outer 22 surface of layer 33 to assume the same temperature 23 aS the hot roll's inner tube, namely 375. As the 24 copy process continues, and at approximately 1.5 seconds into the proces~, control logic 30 operates 26 to close the fusing nip. This is indicated a~ point 27 35 on the curve. From this time until approximately ~8 the 2.5-second time the hot roll and the backup roll .
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, ~ , . . ,, -- _ . ..
~7~69~
1 are in fusing engagement with no sheet interposed 2 be~ween them. As a result of the cooling effect 3 provided by the backup roll, the fusing temperature 4. drops rapidly, following curve 36. At ~7 the first sheet arrives to be fused, and the temperature of 6 the fusing nip has now been cooled approximately 7 to the optimum fusing temperature, namely 340.
8 The backup roll used in FIGURE 3 has a 9 cooling effect somewhat greater than the sheets to be fused. A preferred feature is that the backup .11 roll must cool the hot roll at least as well as sheets 12 to be fused.
13 For comparison, dotted line 38 plot~ the 14 fusing temperature of a hot roll, having a thick.
deformable elastomeric heat insulating coating when 16 early closure o~ the fusing nip is not provided.
17 In this case, at least the first sheet is subjected 18 to an average fusing temperature o about 370, and 19 sticking to the hot roll is likely.to occur.
Preferably, the hot roll and backup roll 21 may be constructed to have diameters in the range 22 of from 1 to 5 inchesi the deformable elastomeric .
23 heat insulating coating on the hot roll may have 24 a-thickness in the range of from .02 to .06 inch;.
and the surface velocity of the rolls is such as 26. to achieve a sheet velocity, through the fusing nip, 27 of from 10 to 30 inches per second. As a result, 28 the fusing nip preferably has a width in the range , . . .
.. BO975010 ~ '' .
~7~694 1 of from .1 to .4 inch, measured in the direction 2 of roll rotation.
3 While the invention has been particularly 4 shown and described with reference to a preferred embodiment thereof, it will be understood by those 6 skilled ln the art that various changes in form and 7 details may be made therein without departing from 8 the spirit and scope of the invention.
9 What is claimed is:
' ' . ' , ' ' ~ , .
., .
.
.
.
, : - : .. . : : :. . .
Claims (6)
1. Dry release hot roll fusing apparatus, comprising:
a dry hot fusing roll having a relatively thick exterior coating, said coating comprising a deformable elastomeric heat insulating surface;
a heater mounted within said hot roll;
a rigid surface backup roll adapted to be force biased against said hot roll to deform the surface of said hot roll to form a fusing nip; and control means operable to close said fusing nip prior to arrival of the first sheet to be fused, the early closure of said fusing nip being such as to cause at least one revolution of said hot roll prior to arrival of the first sheet to be fused.
a dry hot fusing roll having a relatively thick exterior coating, said coating comprising a deformable elastomeric heat insulating surface;
a heater mounted within said hot roll;
a rigid surface backup roll adapted to be force biased against said hot roll to deform the surface of said hot roll to form a fusing nip; and control means operable to close said fusing nip prior to arrival of the first sheet to be fused, the early closure of said fusing nip being such as to cause at least one revolution of said hot roll prior to arrival of the first sheet to be fused.
2. The hot roll fusing apparatus defined in Claim 1 wherein said hot roll comprises a metal tube upon whose exterior surface said coating is placed to form the outer surface thereof, and including temperature sensing and control means cooperating with said core and operable to maintain said core at a selected temperature, said selected temperature being such as to maintain said fusing nip at an optimum fusing temperature after a serial stream of sheets are fused, and as a result operating to elevate the exterior surface of said coating above said optimum fusing temperature during standby periods when no sheets are being fused.
3. The hot roll fusing apparatus defined in Claim 2 wherein the cooling effect of said backup roll upon said hot roll is at least equal to that of a sheet to be fused.
4. The hot roll fusing apparatus defined in Claim 3 wherein the diameter of said hot roll is in the range of 1 to 5 inches, and the coating on said hot roll comprises a layer of silicone rubber having a thickness in the range of .02 to .06 inch.
5. The hot roll fusing apparatus defined in Claim 4 wherein the diameter of said backup roll is in the range of from 1 to 5 inches, and the width of said fusing nip is in the range of from .1 to .4 inch.
6. The hot roll fusing apparatus defined in Claim 5 wherein the surface velocity of said rolls is in the range of from 10 to 30 inches per second.
BO975010 -14- ,###
BO975010 -14- ,###
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US57237475 UST947012I4 (en) | 1975-04-28 | 1975-04-28 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1071694A true CA1071694A (en) | 1980-02-12 |
Family
ID=24287522
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA250,131A Expired CA1071694A (en) | 1975-04-28 | 1976-04-13 | Dry hot roll fusher having early fusing nip closure |
Country Status (7)
| Country | Link |
|---|---|
| US (1) | UST947012I4 (en) |
| JP (1) | JPS51131634A (en) |
| AU (1) | AU498229B2 (en) |
| CA (1) | CA1071694A (en) |
| DE (1) | DE2616804A1 (en) |
| FR (1) | FR2309909A1 (en) |
| GB (1) | GB1482403A (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4162847A (en) * | 1977-10-06 | 1979-07-31 | International Business Machines Corporation | Hot roll fuser early closure inhibitor |
| JPS56142563A (en) * | 1980-04-07 | 1981-11-06 | Canon Inc | Fixing device |
| JPS5972464A (en) * | 1983-07-27 | 1984-04-24 | Canon Inc | Fixing device |
| US5693243A (en) * | 1994-05-09 | 1997-12-02 | Minnesota Mining And Manufacturing Company | Method and apparatus for heat treatment of an element by treatment devices engaging the element on both sides |
-
1975
- 1975-04-28 US US57237475 patent/UST947012I4/en active Pending
-
1976
- 1976-03-02 FR FR7606744A patent/FR2309909A1/en active Granted
- 1976-03-15 GB GB10215/76A patent/GB1482403A/en not_active Expired
- 1976-03-26 JP JP51032716A patent/JPS51131634A/en active Pending
- 1976-04-13 CA CA250,131A patent/CA1071694A/en not_active Expired
- 1976-04-15 DE DE19762616804 patent/DE2616804A1/en not_active Withdrawn
- 1976-04-28 AU AU13430/76A patent/AU498229B2/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| GB1482403A (en) | 1977-08-10 |
| FR2309909B1 (en) | 1979-07-20 |
| FR2309909A1 (en) | 1976-11-26 |
| JPS51131634A (en) | 1976-11-16 |
| UST947012I4 (en) | 1976-06-01 |
| AU1343076A (en) | 1977-11-03 |
| DE2616804A1 (en) | 1976-11-11 |
| AU498229B2 (en) | 1979-02-22 |
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| Date | Code | Title | Description |
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| MKEX | Expiry |