Patent Publication Number: US-8977179-B2

Title: Externally heated fuser assembly for variable sized media

Description:
CROSS REFERENCES TO RELATED APPLICATIONS 
     This application claims priority to U.S. Provisional Patent Application Ser. No. 61/836,904, filed Jun. 19, 2013, entitled “Externally Heated Fuser Assembly for Variable Sized Media,” the content of which is hereby incorporated by reference in its entirety. 
    
    
     BACKGROUND 
     1. Field of the Disclosure 
     The present disclosure relates generally to fusers used in electrophotographic image forming devices and more particularly to an externally heater fuser assembly for variable sized media. 
     2. Description of the Related Art 
     In an externally heated fuser assembly for an electrophotographic image forming device, a heating lamp radiates heat onto the outer surface of a fusing roll or belt. The heated fusing roll or belt is pressed against a backup roll or belt forming a fusing nip. The heating lamp extends the full width of the printing process in order to suitably heat and fuse toner to the widest media sheets used with the image forming device. The fusing heat is controlled by measuring the temperature of the fusing roll or belt and feeding the temperature information to a microprocessor-controlled power supply in the image forming device. The power supply applies power to the heating lamp when the temperature sensed drops below a first predetermined level and interrupts power when the temperature exceeds a second predetermined level. In this way, the fuser assembly is maintained at temperature levels suitable for fusing toner to media sheets without overheating. 
     When printing, the media sheet removes heat from the fuser assembly in the portion of the fuser that contacts the media. When printing on media sheets having widths that are less than the widest media width on which the image forming device is capable of printing, the portion of the fuser assembly beyond the width of the media sheet does not lose heat through the sheet and becomes hotter than the portion of the fuser assembly that contacts the media sheet. In order to prevent thermal damage to components of the fuser assembly, steps are taken to limit the overheating of the portion of the fuser assembly that does not contact narrower media sheets. Typically, the inter-page gap between successive media sheets being printed is increased when media sheets less than the full width are used. However, increasing the inter-page gap between successive media sheets slows the process speed of the image forming device which may lead to customer dissatisfaction. Accordingly, an improved fuser assembly for use with printing on narrower media sheets is desired. 
     SUMMARY 
     A fuser assembly for an electrophotographic image forming device according to one example embodiment includes a rotatable fusing member forming a fusing nip with a backup member. A heating lamp is positioned to heat the fusing member. A first reflector is positioned around a circumferential portion of the fusing member and positioned to direct light from the heating lamp onto the fusing member. The first reflector covers a first section of an axial length of the fusing member and does not cover a second section of the axial length of the fusing member. A second reflector is movable between a first position covering at least a portion of the second section of the axial length of the fusing member and a second position uncovering at least a portion of the second section of the axial length of the fusing member. 
     A fuser assembly for an electrophotographic image forming device according to another example embodiment includes a rotatable fusing member forming a fusing nip with a backup member. A heating lamp is spaced from the fusing member and positioned to supply radiant heat to the fusing member. A first reflector is positioned around a circumferential portion of the fusing member and positioned to direct light from the heating lamp onto the fusing member. The first reflector covers a first section of an axial length of the fusing member extending from a first axial end of the fusing member toward a second axial end of the fusing member. The first reflector does not cover a second section of the axial length of the fusing member near the second axial end of the fusing member. A second reflector is movable toward and away from the second axial end of the fusing member between a first position covering at least a portion of the second section of the axial length of the fusing member and a second position uncovering at least a portion of the second section of the axial length of the fusing member. A heat removal assembly is configured to remove heat collected proximate to the second axial end of the fusing member. 
     An electrophotographic image forming device according to one example embodiment includes a rotatable fusing member forming a fusing nip with a backup member. A heating lamp is spaced from the fusing member and positioned to supply radiant heat to the fusing member. A first reflector is positioned around a circumferential portion of the fusing member and positioned to direct light from the heating lamp onto the fusing member. The first reflector covers a first section of an axial length of the fusing member extending from a first axial end of the fusing member toward a second axial end of the fusing member. The first reflector does not cover a second section of the axial length of the fusing member near the second axial end of the fusing member. A second reflector is movable toward and away from the 10 second axial end of the fusing member between a first position covering at least a portion of the second section of the axial length of the fusing member and a second position uncovering at least a portion of the second section of the axial length of the fusing member. A controller is configured to move the second reflector toward the first position when printing wider media and to move the second reflector toward the second position when printing narrower media. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings incorporated in and forming a part of the specification, illustrate several aspects of the present disclosure, and together with the description serve to explain the principles of the present disclosure. 
         FIG. 1  is a schematic diagram of an image forming device according to one example embodiment. 
         FIG. 2  is a side cross-sectional view of an externally heated fuser assembly according to one example embodiment. 
         FIG. 3  is a front perspective view of the fuser assembly according to one example embodiment. 
         FIG. 4  is an exploded view of the fuser assembly shown in  FIG. 3 . 
         FIG. 5  is a cutaway view of the fuser assembly shown in  FIG. 3  showing a movable reflector in a closed position for wide media according to one example embodiment. 
         FIG. 6  is a cutaway view of the fuser assembly shown in  FIG. 3  showing the movable reflector in an open position for narrow media according to one example embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     In the following description, reference is made to the accompanying drawings where like numerals represent like elements. The embodiments are described in sufficient detail to enable those skilled in the art to practice the present disclosure. It is to be understood that other embodiments may be utilized and that process, electrical, and mechanical changes, etc., may be made without departing from the scope of the present disclosure. Examples merely typify possible variations. Portions and features of some embodiments may be included in or substituted for those of others. The following description, therefore, is not to be taken in a limiting sense and the scope of the present disclosure is defined only by the appended claims and their equivalents. 
     Referring now to the drawings, and more particularly to  FIG. 1 , there is shown a schematic view of an example image forming device  100 . Image forming device  100  includes a housing  110  having a top  111 , bottom  112 , front  113  and rear  114 . Housing  110  includes one or more media input trays  120  positioned therein. Trays  120  are sized to contain a stack of media sheets. As used herein, the term media is meant to encompass not only paper but also labels, envelopes, fabrics, photographic paper or any other desired substrate. Trays  120  are preferably removable for refilling. A media path  106  extends through image forming device  100  for moving the media sheets through the image transfer process. Media path  106  includes a simplex path  107  and may also include a duplex path as desired. A media sheet is introduced into simplex path  107  from tray  120  by a pick mechanism  122 . In the example embodiment shown, pick mechanism  122  includes a roll  124  positioned at the end of a pivotable arm  126 . Roll  124  rotates to move the media sheet from tray  120  into media path  106 . The media sheet is then moved along media path  106  by various transport rolls  108 . Media sheets may also be introduced into media path  106  by a manual feed  128  having one or more rolls  129 . 
     In the example embodiment shown, image forming device  100  includes four toner cartridges (or toner bottles)  130  removably mounted in housing  110  in a mating relationship with four corresponding imaging units  140  also removably mounted in housing  110 . For purposes of clarity, the components of only one of the imaging units  140  are labeled in  FIG. 1 . Each toner cartridge  130  includes a reservoir  132  for holding the main toner supply for image forming device  100  and an outlet port in communication with an inlet port of its corresponding imaging unit  140  for transferring toner from reservoir  132  to a reservoir  142  in the imaging unit  140 . For example, in one embodiment toner moves through a chute that connects the outlet port of a toner cartridge  130  to the inlet port of the corresponding imaging unit  140 . Toner is transferred periodically from a respective toner cartridge  130  to its corresponding imaging unit  140  in order to replenish the imaging unit  140 . In the example embodiment illustrated, each toner cartridge  130  is substantially the same except for the color of toner contained therein. In one embodiment, the four toner cartridges  130  include yellow, cyan, magenta and black toner, respectively. 
     Each imaging unit  140  includes toner reservoir  142  which holds toner received from the corresponding toner cartridge  130  and a photoconductive drum  146 . Photoconductive drums  146  are mounted substantially parallel to each other when the imaging units  140  are installed in image forming device  100 . In the example embodiment illustrated, each imaging unit  140  is substantially the same except for the color of toner contained therein. Each photoconductive drum  146  forms a nip with a corresponding charging roll  148 . During a print operation, charging roll  148  charges the surface of photoconductive drum  146  to a specified voltage such as, for example, −1000 volts. A laser beam from a laser scan unit  116  is then directed to the surface of each photoconductive drum  146  and selectively discharges those areas it contacts to form a latent image. In one embodiment, areas on photoconductive drum  146  illuminated by the laser beam are discharged to a specified voltage, such as approximately −300 volts. Toner stored in reservoir  142  is applied to the areas of the surface of photoconductive drum  146  discharged by the laser beam from LSU  116  to form a toned image on the surface of photoconductive drum  146 . 
     In one embodiment, imaging units  140  utilize a dual component development system. In this embodiment, the toner in each reservoir  142  is mixed with magnetic carrier beads. The magnetic carrier beads may be coated with a polymeric film to provide triboelectric properties to attract toner to the carrier beads as the toner and the magnetic carrier beads are mixed in reservoirs  142 . Magnetic rolls  144  attract the magnetic carrier beads having toner thereon to magnetic roll  144  through the use of magnetic fields and transfer toner to the areas on the surface of the photoconductive drum  146  discharged by the laser beam from LSU  116 . 
     In another embodiment, imaging units  140  utilize a single component development system. In this embodiment, each imaging unit  140  includes a toner adder roll and a developer roll. The toner adder roll moves toner from reservoir  142  to the developer roll. A metering device such as a doctor blade meters toner onto the developer roll and applies a desired charge on the toner. The developer roll forms a nip with the photoconductive drum  146  of the imaging unit  140  and transfers toner to the areas on the surface of the photoconductive drum  146  discharged by the laser beam from LSU  116 . 
     An intermediate transfer mechanism (ITM)  150  is disposed adjacent to the photoconductive drums  146 . ITM  150  is formed as an endless belt trained about a drive roll  152  and backup rolls  154 ,  156 . During image forming operations, ITM  150  moves past photoconductive drums  146  in a clockwise direction as viewed in  FIG. 1 . One or more of photoconductive drums  146  apply toner images in their respective colors to ITM  150  at a first transfer nip  157 . In one embodiment, a positive voltage field attracts the toner image from photoconductive drums  146  to the surface of the moving ITM  150 . ITM  150  rotates and collects the one or more toner images from photoconductive drums  146  and then conveys the toner images to a media sheet at a second transfer nip  158  formed by a transfer roll  159  and backup rolls  154 ,  156 . 
     A media sheet advancing through simplex path  107  receives the toner image from ITM  150  as it moves through the second transfer nip  158 . The media sheet with the toner image is then moved along the media path  106  and into a fuser  200 . As discussed in greater detail below, fuser  200  includes a fusing roll (or belt)  202  that forms a fusing nip  204  with a backup belt (or roll)  206 . In general terms, fuser  200  applies heat and pressure to the media sheets to adhere the toner image to the media sheet. The fused media sheet then passes through exit rolls  160  located downstream from fuser  200 . In some embodiments, exit rolls  160  may be rotated in either forward or reverse directions. In a forward direction, exit rolls  160  move the media sheet from simplex path  107  to an output area  162  on top  111  of image forming device  100 . In a reverse direction, exit rolls  160  move the media sheet into a duplex path as desired for image formation on a second side of the media sheet. 
     While the example image forming device  100  shown in  FIG. 1  illustrates four toner cartridges  130  and four corresponding imaging units  140 , it will be appreciated that a monocolor image forming device  100  may include a single toner cartridge  130  and corresponding imaging unit  140  as compared to a color image forming device  100  that may include multiple toner cartridges  130  and imaging units  140 . Further, although image forming device  100  illustrated utilizes ITM  150  to transfer toner to the media, toner may be applied directly to the media by the one or more photoconductive drums  146  as is known in the art. It will be appreciated that the configurations and architectures of toner cartridge  130  and imaging unit  140  are merely provided as examples and are not intended as limiting. Other configurations and architectures may be used as desired. For example, toner cartridge  130  and imaging unit  140  may be formed as a single replaceable unit instead of separate replaceable units or each imaging unit  140  may be split into multiple replaceable units. Further, one or more components housed in imaging unit  140  may instead be housed in toner cartridge  130  or vice versa. For example, toner cartridge  130  may include reservoir  132 , a toner adder roll and a developer roll forming a first replaceable unit and imaging unit  140  may include photoconductive drum  146  and a waste toner removal system forming a second replaceable unit. 
     Image forming device  100  includes a controller  102 . Controller  102  includes a processor unit and associated memory  103  and may be formed as one or more Application Specific Integrated Circuits (ASICs). Memory  103  may be any volatile or non-volatile memory or combination thereof such as, for example, random access memory (RAM), read only memory (ROM), flash memory and/or non-volatile RAM (NVRAM). Alternatively, memory  103  may be in the form of a separate electronic memory (e.g., RAM, ROM, and/or NVRAM), a hard drive, a CD or DVD drive, or any memory device convenient for use with controller  102 . Controller  102  controls the operation of image forming device  100  and processes print data. As desired, image forming device  100  may include an integrated scanner system for document scanning and copying. In this embodiment, controller  102  may be a combiner printer and scanner controller. It is understood that controller  102  may be implemented as any number of controllers and/or processors for suitably controlling image forming device  100  to perform, among other functions, printing operations. 
     In one embodiment, image forming device  100  includes a user interface (not shown) mounted on an exterior portion of housing  110 . Using the user interface, a user is able to enter commands and generally control the operation of the image forming device  100 . For example, the user may enter commands to switch modes (e.g., color mode, monochrome mode), view the number of pages printed, etc. 
       FIG. 2  shows a cross-sectional view of fuser  200  according to one example embodiment. Fusing nip  204  of fuser  200  is formed between fusing roll  202  and backup belt  206 . Fusing roll  202  may include a metallic core covered with an elastomeric layer, such as silicone rubber, and a fluororesin release layer, such as may be formed, for example, by a spray coated PFA (polyperfluoroalkoyx-tetrafluoroethylene) layer, a PFA-PTFE (polytetrfluoroethylene) blended layer, or a PFA sleeve. Backup belt  206  is an endless belt trained about backup rolls  208 ,  209 . Backup belt  206  may include a stainless steel tube; an elastomeric layer, such as silicone rubber layer, covering the stainless steel tube; and a release layer, such as PFA, sleeve or coating covering the elastomeric layer. The release layers of fusing roll  202  and backup belt  206  are formed on the respective outer surfaces of fusing roll  202  and backup belt  206  so as to contact media sheets passing between fusing roll  202  and backup belt  206 . The release layers prevent contamination from toner particles. Backup belt  206  is biased against fusing roll  202  to apply pressure to a media sheet passing through fusing nip  204  to fuse the toner to the media sheet. As shown in  FIG. 2 , the bias of backup belt  206  causes a portion  206 A of backup belt  206  to bend and conform to the shape of the outer surface of fusing roll  202  increasing the surface area of backup belt  206  in contact with fusing roll  202  to ensure sufficient contact between fusing roll  202  and a media sheet passing through fusing nip  204 . One or more media guides  210  may be positioned upstream and/or downstream from fusing nip  204  to guide the media into fusing nip  204  and from fusing nip  204  to transport rolls that continue to feed the media along media path  106 . 
     With reference to  FIGS. 2-4 , a lamp  212  positioned on the non-contact side of fusing roll  202  (as opposed to the contact side of fusing roll  202  that contacts backup belt  206 ) supplies radiant heat to fusing roll  202  to maintain fusing roll  202  within a desired temperature range. The heated fusing roll  202  fuses the toner to media sheets passing through fusing nip  204 . In one embodiment, lamp  212  includes a halogen bulb that is spaced from the outer surface of fusing roll  202  on the non-contact side of fusing roll  202  and that extends substantially the entire axial length of fusing roll  202  from a first end  202 A of fusing roll  202  to a second end  202 B. As shown in  FIG. 3 , lamp  212  may be supported at its ends  212 A,  212 B ( FIG. 4 ) by end caps  214 ,  216 . As shown in  FIG. 2 , a substantially transparent (e.g., quartz) media shield  218  may be positioned between lamp  212  and fusing roll  202  in order to prevent a misfed media sheet from contacting lamp  212 . 
     A first reflector  220  having a highly reflective inner surface (i.e., the surface facing fusing roll  202 ) wraps around lamp  212  and the non-contact side of fusing roll  202  to redirect light emitted by lamp  212  toward fusing roll  202 . Reflector  220  extends along the axial length of fusing roll  202  from end  202 A of fusing roll  202  toward end  202 B. Reflector  220  does not cover at least a portion of the axial length of fusing roll  202  near end  202 B. A second reflector  230  having a highly reflective inner surface is movable between a first position covering the portion of fusing roll  202  near end  202 B uncovered by reflector  220  and a second position uncovering the portion of fusing roll  202  near end  202 B uncovered by reflector  220 . Reflector  230  is selectively movable between the first position and the second position including positions intermediate the first and second positions to allow heat accumulating near end  202 B of fusing roll  202  to escape to a heat removal assembly  240 . 
     In the example embodiment shown in  FIG. 4 , reflector  220  extends substantially the entire axial length of fusing roll  202  and includes a solid portion  222  and an aperture  224  formed in reflector  220 . Solid portion  222  extends from one end  220 A of reflector  220  toward the other end  220 B of reflector  220 . Aperture  224  is formed as a cutout in reflector  220  near end  220 B of reflector  220 . Aperture  224  extends from near end  220 B along the length of reflector  220  to solid portion  222 . In one embodiment, reflector  220  is mounted in a substantially fixed position relative to lamp  212 . With reference to  FIGS. 5 and 6 , fuser  200  is shown with a portion of heat removal assembly  240  cut away to more clearly illustrate the operation of reflector  230 .  FIG. 5  shows reflector  230  in a closed position covering aperture  224  of reflector  220  blocking heat from escaping fusing roll  202  toward heat removal assembly  240 .  FIG. 6  shows reflector  230  slid to the left as viewed in  FIG. 6  in an open position uncovering aperture  224  of reflector  220  in order to permit heat accumulating near end  202 B of fusing roll  202  to escape to heat removal assembly  240 . In an alternative embodiment, the length of reflector  220  is less than the length of fusing roll  202  and reflector  220  extends from end  202 A of fusing roll  202  toward, but not all the way to, end  202 B of fusing roll  202 . In this embodiment, reflector  230  is movable between a closed position covering the gap between reflector  220  and end  202 B of fusing roll  202  and an open position exposing at least a portion of the gap between reflector  220  and end  202 B of fusing roll  202 . Any suitable actuation mechanism may be used to move reflector  230  toward and away from end  202 B of fusing roll  202 . For example, reflector  230  may be driven by an electric motor and gear system or actuated by a solenoid. 
     In one embodiment, the inner surfaces of reflector  220  and reflector  230  are parabolic in cross-section along the axial length of fusing roll  202  and lamp  212 . It is believed that a parabolic shape distributes the light from lamp  212  across the outer circumference of the non-contact side of fusing roll  202  exposed to reflectors  220  and  230 . In contrast, an elliptical reflective surface may tend to focus the light from lamp  212  along a thin band running the axial length of fusing roll  202  potentially damaging fusing roll  202  if fusing roll  202  is not rotating while lamp  212  is on. For example, a thin band exposure may result in a “sunburn” condition where a gloss streak is formed on the outer surface along the axial length of fusing roll  202 . However, the reflective surfaces of reflector  220  and  230  may take any suitable cross-sectional shape provided that light from lamp  212  is not focused on the outer surface of fusing roll  202  in a manner that damages fusing roll  202 . 
     With reference back to  FIG. 3 , in the example embodiment illustrated, the inner surface of each end cap  214 ,  216  is also reflective in order to redirect light from lamp  212  toward fusing roll  202 . In this manner, the amount of light wasted from lamp  212  (i.e., the amount of light not used for heating fusing roll  202 ) is minimized. Belt and hot roll fuser assemblies commonly utilize a lamp having increased illumination at its axial ends in order to provide relatively uniform heating across the axial length of the fusing roll. The reflective inner surfaces of end caps  214 ,  216  may eliminate the need for greater illumination at the axial ends of lamp  212  permitting substantially uniform illumination along the length of lamp  212  thereby reducing the cost of lamp  212 . 
     With reference to  FIGS. 2-4 , heat removal assembly  240  includes a heat collector  242  that wraps around the exterior of reflectors  220  and  230 . Collector  242  is composed of a thermally conductive material and possesses a high emissivity (e.g., ε&gt;˜0.96). For example, in one embodiment, collector  242  is composed of black, high temperature painted aluminum. Collector  242  shrouds reflectors  220  and  230  in order to absorb the radiate heat transfer from lamp  212 . Collector  242  is in turn adjoined to a heat sink  244  that transfers the heat away from fusing roll  202 . In the embodiment illustrated, heat sink  244  includes a heat pipe  246  that transfers heat energy collected at end  202 B of fusing roll  202  toward a convective fin arrangement  248  where air flow from a fan mounted in image forming device  100  removes the heat energy from fuser  200 . Heat pipes are known to transfer heat using thermal conductivity and phase transition. In general terms, heat pipe  246  may include a vessel in which its inner walls are lined with a wick structure. When the heat pipe is heated at one end (near end  202 B), the working fluid therein evaporates and changes phase from liquid to vapor. The vapor travels toward the cool end (toward end  202 A of fusing roll  202 ) through the hollow core of the heat pipe and back to the hot end (toward end  202 B of fusing roll  202 ) via the wick structure by capillary action and is then available to repeat the heat transfer process. In the example embodiment illustrated, convective fin arrangement  248  is positioned on a portion of heat sink  244  proximate to end  202 A of fusing roll  202 . In another embodiment, convective fin arrangement  248  is spaced away from fuser  200  and may be positioned in a remote location with respect to fuser  200  within image forming device  100  in order to provide a more convenient placement for convective fin arrangement  248  and the associated fan and airflow. In this embodiment, heat pipe  246  extends from heat sink  244  through image forming device  100  and connects to convective fin arrangement  248  in order to transfer heat from heat sink  244  to convective fin arrangement  248 . Thermal grease or gel may be used in any gaps between collector  242  and heat sink  244  or within heat sink  244  in order to improve the thermal dissipation. To the extent possible, the components of collector  242  and heat sink  244  are formed integrally in order to promote heat transfer. 
     With reference back to  FIGS. 5 and 6 , in one embodiment, the position of reflector  230  is based on the width of the media passing through fusing nip  204 . For the widest media supported by image forming device  100 , reflector  230  is positioned adjacent to end  202 B of fusing roll  202  covering aperture  224  of reflector  220  in order to uniformly heat fusing roll  202  along the entire length of fusing roll  202 . As discussed above, when printing media that is narrower than the widest media supported by image forming device  100 , the portion of fusing roll  202  beyond the width of the media does not lose heat through the sheet and becomes hotter than the portion of fusing roll  202  that contacts the media sheet. Accordingly, for media that is narrower than the widest media supported, reflector  230  may be moved to uncover a portion of fusing roll  202  (e.g., via aperture  224 ) in order to permit heat accumulating near end  202 B of fusing roll  202  to escape. For example, reflector  230  may be moved to align an edge  232  of reflector  230  with the edge of the media passing through fusing nip  204  in order to permit heat accumulating beyond the width of the media to escape. For example, if the widest media supported by image forming device  100  is letter sized media and A4 media, which is 6 mm narrower than letter sized media, is printed reflector  230  may be moved to align edge  232  with the edge of the A4 media, which is spaced inward from end  202 B of fusing roll  202 . With reflector  230  slid away from end  202 B of fusing roll  202 , heat is permitted to radiate to collector  242  (instead of being reflected back onto fusing roll  202 ) and ultimately to heat pipe  246  which transfers the heat to convective fin arrangement  248  where the heat is removed by passing air. As a result, image forming device  100  is permitted to print narrow media at normal process speeds for an improved period of time. 
     Reflector  230  may change positions in response to any suitable input or condition. The position of reflector  230  may be based on a command received at the user interface. For example, a user may select the media size to be printed on and reflector  230  may move to a predetermined positioned based on the media size selected. The media selection may be communicated to controller  102  and controller  102  may then control the operation of the actuation mechanism that positions reflector  230 . The position of reflector  230  may also be based on the size of the media being printed such as by sensing the size of the media in the media input tray  120  from which media sheets are fed for printing or by sensing the size of the media traveling along media path  106 . For example, it is common for media input trays  120  to include one or more manually movable media walls that are positioned at the edges of a stack of media sheets in order to maintain a neatly aligned stack. Positioning sensors may be used to communicate the position(s) of the media wall(s) to controller  102 . Controller  102  may then use this positional information to determine the media size and position reflector  230  accordingly. The position of reflector  230  may also be based on temperature data received from one or more temperature sensors  250  ( FIG. 2 ), e.g., one or more non-contact thermistors, positioned along fusing roll  202 . For example, temperature sensor(s)  250  may be used to determine when the temperature near end  202 B of fusing roll  202  is greater than the temperature near end  202 A of fusing roll  202  or at other points along fusing roll  202  indicating that narrow media is being printed. This temperature information may be communicated to controller  102  and controller  102  may adjust the position of reflector  230  in order to permit excess heat to dissipate near end  202 B of fusing roll  202 . Alternatively, the temperature information may indicate that too much heat is dissipating near end  202 B prompting controller  102  to close reflector  230  in order to prevent end  202 B of roll  202  from cooling excessively. In general terms, when the temperature sensed drops below a first predetermined level, lamp  212  is turned on to heat fusing roll  202  and when the temperature exceeds a second predetermined level, lamp  212  is turned off. These temperature settings are typically based on power considerations of image forming device  100  as well as the properties of the toner being used (e.g., the melting properties of the toner). 
     The foregoing description illustrates various aspects of the present disclosure. It is not intended to be exhaustive. Rather, it is chosen to illustrate the principles of the present disclosure and its practical application to enable one of ordinary skill in the art to utilize the present disclosure, including its various modifications that naturally follow. All modifications and variations are contemplated within the scope of the present disclosure as determined by the appended claims. Relatively apparent modifications include combining one or more features of various embodiments with features of other embodiments.