Source: http://www.google.com/patents/US6721518?dq=5920316
Timestamp: 2013-12-10 03:11:06
Document Index: 274171548

Matched Legal Cases: ['art 112', 'art 112', 'arts 150', 'arts 152', 'art 150', 'art 152']

Patent US6721518 - Thermal fuser and image formation apparatus - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Advanced Patent Search | Sign inAdvanced Patent SearchPatentsThe part of a halogen heater 90 corresponding to the position of a temperature sensing member 110 is positioned at a part where the temperature gradient of light distribution ripple 120 along the length direction of the halogen heater 90 is moderate (a top 122 or a bottom 124)....http://www.google.com/patents/US6721518?utm_source=gb-gplus-sharePatent US6721518 - Thermal fuser and image formation apparatusPublication numberUS6721518 B2Publication typeGrantApplication numberUS 09/988,362Publication dateApr 13, 2004Filing dateNov 19, 2001Priority dateNov 20, 2000Fee statusPaidAlso published asUS20020061201Publication number09988362, 988362, US 6721518 B2, US 6721518B2, US-B2-6721518, US6721518 B2, US6721518B2InventorsHideo Oshida, Yasuki Tanaka, Keiji Sanekata, Hitoshi NanbaOriginal AssigneeFuji Xerox Co., Ltd.Export CitationBiBTeX, EndNote, RefManPatent Citations (12), Referenced by (4), Classifications (7), Legal Events (3) External Links: USPTO, USPTO Assignment, EspacenetThermal fuser and image formation apparatusUS 6721518 B2Abstract The part of a halogen heater 90 corresponding to the position of a temperature sensing member 110 is positioned at a part where the temperature gradient of light distribution ripple 120 along the length direction of the halogen heater 90 is moderate (a top 122 or a bottom 124).
SUMMARY OF THE INVENTION It is an object of the invention to solve the above-described problems by devising placement of a heating source to thin a heating roll for lessening the heat capacity of the heating roll and provide an excellent thermal fuser and an excellent image formation apparatus without producing any disadvantage by simple improvement in the configuration.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a transverse sectional view of a heating roll of an embodiment.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the invention, for example, a unit for controlling power on/off, voltage, etc., may be used as a unit for controlling the electric power supplied to a heating source based on the temperature sensed by a temperature sensing member. In a first embodiment, the heating source contained in the heating roll is placed closely to an excessive temperature rising prevention device from the center of the heating roll and the heating source has the larger heating value, the heating source is placed closer to the excessive temperature rising prevention device from the center of the heating roll. If the thickness of the heating roll is thinned, when a control circuit runs away for some reason, a problem of the excessive temperature rising prevention device incapable of responding to the runaway occurs. Particularly, when the roll stops and paper is caught in the roll, there is a possibility that the paper caught in the roll may catch fire, etc., to increase the danger. According to the first embodiment of the invention, the heating source is brought closely to the excessive temperature rising prevention device so that the danger can be circumvented.
First Embodiment FIG. 1 shows the first embodiment of the invention and shows the cross section of the heating roll 10 and the pressure member 20. The heating sources (halogen heaters 12 and 14) are brought closely to the excessive temperature rising prevention device 30 from the center of the heating roll 10. The heating source has the larger heating value, the heating source is disposed closer to the excessive temperature rising prevention device 30.
The advantages of the first embodiment of the invention will be discussed with reference to FIGS. 5 to 9. FIG. 5 shows the progression of the heating roll temperature when an excessive temperature rising (temperature controller failure) occurs in the related art wherein the heating source (750-W halogen heater) is placed at the center of the heating roll. Paper nip side temperature 60 and excessive temperature rising prevention device temperature 62 rise rapidly and lower as the excessive temperature rising prevention device operates. At this time, the paper nip side temperature 60 reaches 450� C. and the excessive temperature rising prevention device temperature 62 also reaches 436� C. The paper nip side temperature 60 exceeds paper-catching-fire danger temperature 64 (about 400� C.). FIG. 6 shows the progression of the heating roll temperature according to the first embodiment of the invention when an excessive temperature rising (temperature controller failure) occurs wherein a 750-W halogen heater is used as the heating source as well as in FIG. 5. The halogen heater is placed closely to the excessive temperature rising prevention device 3 mm from the center of the heating roll. In this case, paper nip side temperature 66 becomes a maximum value of 342� C. and excessive temperature rising prevention device temperature 68 becomes a maximum value of 386� C. The paper nip side temperature 60 does not reach the paper-catching-fire danger temperature 64 (about 400� C.).
FIG. 7 shows the progression of the temperature of the excessive temperature rising prevention device over time when 250 sheets of A3-size paper were printed in the first embodiment of the invention. FIG. 7 shows heating roll temperature 70 at the time of the operation of the fuser 76. Here, the operation of the fuser denotes rotation of the heating roll. FIG. 7 also shows temperature 72 when the cooling air amount in the proximity of the excessive temperature rising prevention device is small and temperature 74 when the cooling air amount is large when a 750-W halogen heater is installed upstream and when a 500-W halogen heater is installed downstream. The excessive temperature rising prevention device temperature 72 indicates 143.6� C. at the maximum and the excessive temperature rising prevention device temperature 74 becomes 135.4� C. at the maximum; the improvement effect is 8.2� C.
Second Embodiment Next, the second embodiment of the invention will be discussed. FIG. 11 is a schematic representation of a related art example; FIG. 11 shows a halogen heater 90, a heating roll 214 containing the halogen heater 90, and a curve 120 (light distribution ripple 120) indicating a surface light distribution graph along an axial direction of the heating roll. The surface temperature graph takes a length direction of the halogen heater 90 as a horizontal axis and the direction at the right angle to the length direction as a vertical axis; the temperature level on the vertical axis is indicated. As the halogen heater 90, a filament 92 provided by winding tungsten wire like a sparse and dense spiral is sealed in a seal tube 94 and is hermetically sealed together with halogen gas 96 and is connected at each end to a power supply terminal 100. The light distribution ripple 120 is shaped locally up and down and is formed with a top 122 and a bottom 124. In FIG. 11, a temperature sensing member 110 is in contact with the outer face of the heating roll 214 for detecting the surface temperature of the heating roll 214. In FIG. 11, a temperature sensing part 112 of the temperature sensing member 110 is at a position not corresponding to any top 122 of the light distribution ripple 120 or any bottom 124. An average temperature of the curve 122 is controlled to be at 180� C.
FIG. 10 is a schematic representation to describe the second embodiment of the invention and shows a halogen heater 90 and light distribution ripple 120 indicating a surface light distribution of a heating roll similar to those previously described with reference to FIG. 11. Reference numerals in FIG. 10 are similar to those in FIG. 11. The average temperature of the curve 122 shown in FIG. 10 is controlled to be at 178� C. In FIG. 10, the position of a temperature sensing member 110 matches the position corresponding to a bottom 124 of the light distribution ripple 120. In doing so, to control the temperature of the heating roll based on the sense temperature of the temperature sensing member 110, what is the detection temperature measured by the temperature sensing member 110 is made clear. Therefore, the accuracy of the temperature control can be improved. In FIG. 10, the part corresponding to the position of the temperature sensing member 110 matches the bottom 124 of the local light distribution ripple 120 in the axial direction of the halogen heater, but may be matched with a top 122.
Third Embodiment Next, the third embodiment of the invention for fixing while changing a plurality of halogen heaters different in light distribution in response to the print conditions of the paper size, the number of print sheets of paper, etc., will be discussed with reference to FIG. 12. FIG. 12 is a transverse sectional view of a heating roll 130 and a pressure member 140. The heating roll 130 contains two halogen heaters 90A and 90B. For example, the halogen heater 90A has a narrow heating area and corresponds to narrow paper and the halogen heater 90B has a wide heating area and corresponds to wide paper. The halogen heaters 90A and 90B are changed for use in response to the print condition. The heating roll 130 rotates in a rotation direction 132 and the pressure member 140 is rotated to follow the rotation of the heating roll 130. The heating roll 130 and the pressure member 140 are pressed against each other and paper is caught in nip 134 therebetween and is passed through between the two rolls (heating roll 130 and pressure member 140). When the paper is passed through the nip 134, toner on the paper is thermally fused to the paper. A temperature sensing member 110 has a temperature detection part 112 brought into contact with the outer surface of the heating roll 130. In such placement, if the temperature sensing member 110 is placed corresponding to the bottom of a light distribution ripple for both the halogen heaters 90A and 90B, temperature 114 of the portion of the nip 134 becomes as shown in FIG. 13. That is, when the halogen heater 90B is used, the portion of the lowest temperature on the roll circumference (upstream from the halogen heater) is monitored and controlled and thus the temperature 114 of the nip 134 becomes high. In contrast, when the halogen heater 90A is used, the portion of the highest temperature on the roll circumference (downstream from the halogen heater) is monitored and controlled and thus temperature 116 of the nip 134 becomes low as shown in FIG. 13.
Fourth Embodiment Next, the fourth embodiment of the invention will be discussed. FIG. 16 is a fragmentary drawing of a halogen heater 90 of a heating source. In the halogen heater 90, a filament 92 is sealed in a seal tube 94 and comprises light emitting parts 150 and non-light emitting parts 152 placed alternately at almost equal intervals along the length direction of the halogen heater 90, and the light emission amount differs in the length direction. In this embodiment, the dimensions of the light emitting part 150 and that of the non-light emitting part 152 in the length direction of the halogen heater are each about 10 mm. A temperature sensing member 110 is disposed almost at the center of the halogen heater 90 in the length direction thereof. The position of the temperature sensing member 110 is at a given distance 154 from one terminal 100. The temperature sensing member 110 senses the temperature of the outer face of a heating roll containing the halogen heater 90. A temperature controller for controlling power of the halogen heater 90 based on the sensed temperature is provided.
Patent CitationsCited PatentFiling datePublication dateApplicantTitleUS4740671 *Oct 30, 1986Apr 26, 1988Canon Kabushiki KaishaTemperature control apparatus for detecting an abnormality in a heater in a copying machine or the likeUS5118920 *Dec 5, 1990Jun 2, 1992Canon Kabushiki KaishaImage fixing apparatusUS5633704 *May 16, 1995May 27, 1997Canon Kabushiki KaishaImage forming apparatus having fixing means error detectionUS5701556 *Dec 7, 1994Dec 23, 1997Fujitsu LimitedThermal fixing device having temperature controlUS5737664 *Jun 15, 1995Apr 7, 1998Oki Electric Industry Co., Ltd.Overheating prevention device for a fixing unitUS5802421 *Aug 28, 1995Sep 1, 1998Canon Kabushiki KaishaHeating and fixing device with AC zero-cross detection circuitUS5848319 *Aug 26, 1997Dec 8, 1998Minolta Co., Ltd.Apparatus discriminating the transport condition of a recording medium through a fixing device based on temperature of a fixing rollerUS6185388 *Feb 22, 1999Feb 6, 2001Canon Kabushiki KaishaImage heating apparatus with standby temperature overshooting prevention featureJP4039077B Title not availableJP4077313B Title not availableJP4077314B Title not availableJPH05333744A Title not available* Cited by examinerReferenced byCiting PatentFiling datePublication dateApplicantTitleUS7386265 *Dec 27, 2005Jun 10, 2008Kyocera Mita CorporationFixing unit having heat roller with two parallel tubular heatersUS7433627Jun 28, 2005Oct 7, 2008Xerox CorporationAddressable irradiation of imagesUS7548719Apr 30, 2008Jun 16, 2009Kyocera Mita CorporationFixing unit including heat roller with tubular heater and fitting surfaceUS7672634Nov 30, 2004Mar 2, 2010Xerox CorporationAddressable fusing for an integrated printing system* Cited by examinerClassifications U.S. Classification399/69, 399/328International ClassificationG03G21/00, G03G15/20, H05B3/00Cooperative ClassificationG03G15/2078European ClassificationG03G15/20H2P3Legal EventsDateCodeEventDescriptionSep 14, 2011FPAYFee paymentYear of fee payment: 8Sep 17, 2007FPAYFee paymentYear of fee payment: 4Nov 19, 2001ASAssignmentOwner name: FUJI XEROX CO., LTD., JAPANFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:OSHIDA, HIDEO;TANAKA, YASUKI;SANEKATA, KEIJI;AND OTHERS;REEL/FRAME:012315/0005Effective date: 20011112Owner name: FUJI XEROX CO., LTD. 17-22, AKASAKA 2-CHOME, MINATFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:OSHIDA, HIDEO /AR;REEL/FRAME:012315/0005RotateOriginal ImageGoogle Home - Sitemap - USPTO Bulk Downloads - Privacy Policy - Terms of Service - About Google Patents - Send FeedbackData provided by IFI CLAIMS Patent Services©2012 Google