Abstract:
A fixing device comprising a fixing unit comprising a heat source for fixing a toner image on a sheet in a state of being out of contact with the sheet, and a contact prevention unit preventing contact of the fixing unit and the sheet.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2007-021251 filed Jan. 31, 2007. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Technical Field 
         [0003]    The present invention relates to a fixing device and fixing method. 
         [0004]    2. Related Art 
         [0005]    Conventionally, as an image forming device of an electrophotographic method, there is an image forming device using a flash fixing method for fixing a toner on a recording media by using a flash lump. 
         [0006]    In the above-described image forming device, a fan is provided between a developing unit and a fixing unit. 
       SUMMARY 
       [0007]    A fixing device of a first aspect of the present invention has a fixing unit provided with a heat source for fixing a toner image on sheet in a state out of contact with the sheet, and a contact prevention unit preventing contact of the fixing unit and the sheet. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    Embodiments of the present invention will be described in detail based on the following figures, wherein: 
           [0009]      FIG. 1  is a cross-sectional view of an image forming device according to a first exemplary embodiment of the present invention; 
           [0010]      FIG. 2A  is a cross sectional view of a fixing device according to the first exemplary embodiment of the invention, and  FIG. 2B  is a front view of a fixing unit according to the first exemplary embodiment of the invention; 
           [0011]      FIGS. 3A and 3B  are schematic diagrams showing a recording paper jam detection method according to the first exemplary embodiment of the invention; 
           [0012]      FIG. 4  is a cross-sectional view showing a state during recording paper jam in the fixing device according to the first exemplary embodiment of the invention; 
           [0013]      FIGS. 5A and 5B  are cross-sectional views of the fixing device according to a second exemplary embodiment of the invention; 
           [0014]      FIGS. 6A to 6C  are cross-sectional views of the fixing device according to a third exemplary embodiment of the invention; and 
           [0015]      FIGS. 7A and 7B  are perspective views of the fixing device according to a fourth exemplary embodiment of the invention. 
       
    
    
     DESCRIPTION 
       [0016]    A first exemplary embodiment of an image forming device of the invention will be described with reference to the drawings. 
         [0017]    As shown in  FIG. 1 , an image forming device  100  for performing flash fixing for fixing by an irradiation heat of a xenon lump or the like after forming an image is provided. 
         [0018]    The image forming device  100  forms the image on recording paper  112 , formed of continuous form paper capable of being cut, as one example of the paper. 
         [0019]    The recording paper  112  inserted into the image forming device  100  from an arrow IN direction is wrapped around wrapping rollers  114  and  116 , and is fed on a feeding path formed so as to cross an inner portion of the image forming device  100  at a constant speed. 
         [0020]    On a lower side of the feeding path of the recording paper  112 , image forming units  118 A,  118 B,  118 C and  118 D for forming toner images of C (cyan), M (magenta), Y (yellow) and K (black), respectively, are arranged along the feeding path at substantially regular intervals therebetween. 
         [0021]    Each of the image forming units  118 A to  118 D is provided with a photosensitive drum  120 , which has the same configuration except the color of the toner image to be formed, and is arranged such that an axis line thereof is orthogonal to a feeding direction of the recording paper  112 . 
         [0022]    A charger  122  for charging the photosensitive drum  120  is provided around the photosensitive drum  120 . An exposure device  124  for irradiating a charged photosensitive drum  120  with an LED light to form an electrostatic latent image is provided on a downstream side of the charger  122  in a rotation direction of the photosensitive drum  120 . 
         [0023]    A developing device  126  for forming the toner image by supplying a toner of a predetermined color to the electrostatic latent image on the photosensitive drum  120  is provided on a downstream side of the exposure device  124 . 
         [0024]    A transferring device  128  arranged so as to be opposed to the photosensitive drum  120  with the feeding path of the recording paper  112  interposed therebetween for transferring the toner image on the recording paper  112  is provided on a downstream side of the developing device  126 . 
         [0025]    A discharger  130  for discharging a surface of the photosensitive drum  120 , a cleaner blade  132  for removing residual toner on the surface of the photosensitive drum  120 , and a cleaner brush  134  are arranged on a downstream side of the transferring device  128 . 
         [0026]    Herein, when printing in color, the image forming units  118 A to  118 D form the toner images of which colors are different to one another on the peripheral surfaces of the photosensitive drums  120  by the chargers  122 , the exposure devices  124 , and the developing devices  126 , and thereafter, transfer the toner images on the recording paper  112  by the transferring devices  128 . 
         [0027]    In a series of process of charge, exposure (electrostatic latent image forming), develop (toner image forming) and transfer in the image forming units  118 A to  118 D, an execution timing thereof is controlled such that the toner images formed at the image forming units  118 A to  118 D are overlapped to one another on the recording paper  112 . Thereby, a full-color toner image is formed on the recording paper  112 . 
         [0028]    Also, when printing monochrome image, the image forming unit  118 D for black is driven to form a black toner image on the peripheral surface of the photosensitive drum  120  by the charger  122 , the exposure device  124  and the developing device  126 , and thereafter, by transferring the toner image on the recording paper  112  by the transferring unit  128 , the black toner image is formed on the recording paper  112 . 
         [0029]    In the feeding path of the recording paper  112 , the feeding direction is changed to a substantially vertical direction by a wrapping roller  138  on a downstream side of positions of the image forming units  118 A to  118 D. 
         [0030]    In a section between the wrapping roller  138  and a wrapping roller  142  at a downstream side of the wrapping roller  138 , the recording paper  112  is fed upward in the substantially vertical direction. A fixing device  10  is arranged on the feeding path between the wrapping rollers  138  and  142 . 
         [0031]    The fixing device  10  is provided with a flash fixing unit  140  as one example of a fixing unit and an air intake unit  11  as one example of an air intake part. 
         [0032]    A tension roller  144  is provided at a downstream side of the wrapping roller  142 . 
         [0033]    Detection part such as a pressure sensor or an optical position sensor not shown is provided on the tension roller  144 . Also, a portion of an outer peripheral side surface of the tension roller  144  abuts the recording paper  112 , and the tension roller  144  is energized in a direction to press the recording paper  112  to a lower side by using a spring or the like. 
         [0034]    Herein, as shown in  FIG. 3A , at the time of ordinary use of the image forming device  100 , the recording paper  112  is tightened with a predetermined tension, and the tension roller  144  is at a position at which the above-described energizing force and the tension of the recording paper  112  are balanced. 
         [0035]    On the other hand, as shown in  FIG. 3B , when a jam occurs and the recording paper  112  is cut, the tension of the recording paper  112  is weakened, so that the position of the tension roller  144  lowers from a general position (two-dot chain line) to a lower position (solid line) by the energizing force. 
         [0036]    By detecting this change in position of the tension roller  144  by the above-described pressure sensor or optical position sensor, the jam of the recording paper  112  is detected. 
         [0037]    Also, as shown in  FIG. 1 , the wrapping rollers  146  and  148  are sequentially arranged at a downstream side of the tension roller  144 , and it is configured that the recording paper  112  on which the toner image is fixed is guided to the wrapping rollers  146  and  148  and is discharged outside of the image forming device  100 . 
         [0038]    Next, the fixing device  10  will be described. 
         [0039]    The fixing device  10  is provided with the flash fixing unit  140  and the air intake unit  11  as described above. 
         [0040]    As shown in  FIG. 2 , the flash fixing unit  140  has a housing  12  in a box-shape one planar surface of which is opened, and is provided with flash lumps  14  in the housing  12 , as one example of six heat sources emitting the flash light. 
         [0041]    The flash lamps  14  emits the flash light by a voltage supplied from a power supply not shown to fuse a toner T on the recording paper  112  by energy of the flash light, thereby fixing the toner image transferred on the recording paper  112 . 
         [0042]    A cover glass  16  is arranged on a front surface side of the flash lamps  14  and the feeding path side of the recording paper  112 . 
         [0043]    The cover glass  16  as one example of a protective glass is fixed to the housing  12  by adhesion to prevent intrusion of dust or the like into the flash fixing unit  140 , and prevents the recording paper  112  and the flash lamps  14  from contacting each other. 
         [0044]    Also, plural penetrating air-through holes  18 ,  19 ,  20  and  21  are formed in the housing  12  so as to enclose the flash lamps  14 . One end of each of stainless pipes  22  and  24  are connected to the air-through holes  18 ,  19 ,  20  and  21 , and other end of each of the pipes are connected to a fan  26 . 
         [0045]    The fan  26  as one example of an air sending part is driven by power supplied by power supply means not shown to supply air to the pipes  22  and  24 . 
         [0046]    Thereby, when the power is supplied to the fan  26  by the power supply means, air is supplied to the pipes  22  and  24 , and air is sent from the air-through holes  18  to  21  toward the recording paper  112 . 
         [0047]    The air sending part is formed from the fan  26 , the pipes  22  and  24 , and the air-through holes  18  to  21 . 
         [0048]    The air intake unit  11  is arranged on a position opposed to the front surface of the flash fixing unit  140  with the feeding path of the recording paper  112  interposed therebetween. 
         [0049]    The air intake unit  11  as one example of a contact prevention unit has a side plate  28 , a duct  32 , an air intake device  34  and a pipe  38 . 
         [0050]    The side plate  28  is fixed so as to be apart from the recording paper  112  by a predetermined distance, and plural air intake holes  30  penetrating toward the recording paper  112 , are formed therein. Also, the duct  32  is provided on a surface opposite to the recording paper  112  of the side plate  28  so as to cover the air intake holes  30 . 
         [0051]    An opening is formed on one end portion of the duct  32 , and the air intake device  34  is fixed to the opening by a screw, an adhesive or the like. Also, an inclined surface to make an air flow be stable during air intake is formed in the duct  32 . 
         [0052]    The air intake device  34  is provided with a fan  36  rotating by driving means such as a motor or the like not shown inside thereof. In addition, a pipe  38  for discharging intaken air outside of the image forming device  100  is connected to the air intake device  34 . 
         [0053]    Thereby, when the air intake device  34  is driven, the fan  36  rotates and intakes air through the air intake holes  30 , and the intaken air is discharged from the duct  32  through the fan  36  to the pipe  38 . 
         [0054]    Note that, the contact prevention unit of this exemplary embodiment is formed of the air sending part from the fan  26  to the air through holes  18  to  21 , and the air intake unit  11 . 
         [0055]    Also, it is configured that when the jam is detected, a jam detection signal is sent to a driving unit not shown and the driving unit drives the fan  26  and the air intake device  34 . 
         [0056]    Next, function of the first exemplary embodiment of the invention will be described. 
         [0057]    As shown in  FIGS. 3 and 4 , when the jam of the recording paper  112  occurs during operation of the image forming device  100  (refer to  FIG. 1 ) and the recording paper  112  is cut, the position of the tension roller  144  lowers and the jam is detected by the above-described sensor. 
         [0058]    The fan  26  (refer to  FIG. 2 ) and the air intake device  34  are driven by the jam detection signal. 
         [0059]    Air sent from an arrow A direction is blown on a recording surface side of the recording paper  112 , and a rear surface side of the recording paper  112  is sucked to a side plate  28  side by the air intaken in an arrow B direction. 
         [0060]    Thereby, the recording paper  112  is kept away from the cover glass  16  of the flash fixing unit  140 . 
         [0061]    Next, a second exemplary embodiment of the fixing device and the image forming device of the invention will be described with reference to the drawings. 
         [0062]    The same reference numeral as that in the above-described first exemplary embodiment is given to the basically same component as that in the above-described first exemplary embodiment, and the description thereof is omitted. 
         [0063]    As shown in  FIGS. 5A and 5B , one end of each of stainless pipes  46  and  48  are connected to the air-through holes  18  and  20  of the flash fixing unit  140 , respectively, and the pipes  46  and  48  are connected to a pipe  44  by a three-way joint not shown and inner sides thereof are communicated to one another. The other end of the pipe  44  is connected to a first fan  42 . 
         [0064]    It is configured that the first fan  42  is driven by the power supplied from power supplying unit not shown, and supplies air to the pipe  44 . 
         [0065]    Thereby, it is configured that when the first fan  42  is driven by the power supplied from the power supplying unit, air is supplied through the pipe  44  to the pipes  46  and  48 , and air is sent from the air-through holes  18  to  21  toward the recording paper  112  in an arrow D direction. 
         [0066]    On the other hand, an air sending unit  40  is arranged on a position opposed to the front surface of the flash fixing unit  140  with the feeding path of the recording paper  112  interposed therebetween. 
         [0067]    The air sending unit  40  as one example of a reverse air sending part has a side plate  50  seperated from the recording paper  112  with a predetermined distance therebetween, a pipe  54 , and a second fan  58 . 
         [0068]    A plurality of air-through holes  52  penetrating toward the recording paper  112  are formed in the side plate  50 . A plurality of pipes  54  are arranged on a surface opposite to the recording paper  112  on the side plate  50 , and the air-through holes  52  and the pipes  54  are connected and fixed. 
         [0069]    The other end of the pipe  54  is connected to one pipe  56  by a joint not shown, and the other end of the pipe  56  is connected to a second fan  58 . 
         [0070]    It is configured that the second fan  58  is driven by the power supplied from power supplying unit not shown to supply air to the pipe  56 . 
         [0071]    Thereby, when the second fan  58  is driven, air is supplied through the pipe  56  to a plurality of pipes  54 , and air is sent from a plurality of air-through holes  52  toward the rear surface of the recording paper  112  in an arrow C direction. 
         [0072]    Next, function of the second exemplary embodiment of the invention will be described. 
         [0073]    In the image forming device  100  (refer to  FIG. 1 ), the second fan  58  is driven during fixation on the recording paper  112 . Air supplied from the second fan  58  is sent through the pipes  56  and  54  in the arrow C direction. 
         [0074]    Thereby, the recording paper  112  gets close to a flash fixing unit  140  side by air sent from the arrow C direction, and heat by light emission of the flash lumps  14  is transmitted to the toner T on the recording paper  112 . 
         [0075]    On the other hand, when the recording paper  112  is cut during the jam of the recording paper  112 , the jam detection device in the above-described tension roller  144  (refer to  FIG. 3 ) activates to drive the first fan  42 . Air sent from the first fan  42  is sent from the pipe  44  through the pipe  46  or  48  in the arrow D direction. 
         [0076]    Thereby, the recording paper  112  is kept apart from the cover glass  16 . 
         [0077]    Next, a third exemplary embodiment of the fixing device and the image forming device of the invention will be described with reference to the drawings. 
         [0078]    The same reference numeral as that in the above-described first exemplary embodiment is given to the basically same component as that in the above-described first exemplary embodiment, and the description thereof is omitted. 
         [0079]    As shown in  FIGS. 6A to 6C , a flash fixing unit  70  is provided in the image forming device  100 . 
         [0080]    In the flash fixing unit  70  as one example of the fixing unit, flash lumps  74  as one example of six heat sources are arranged in a housing  72  in a box-shape having an opening on one side, and the opening is covered with the cover glass  76 . 
         [0081]    An electrostatic absorption device  60  is arranged at a position opposed to the cover glass  76  with a predetermined distance therebetween. 
         [0082]    The electrostatic absorption device  60  as one example of electrostatic force generation part is configured such that a plastic composite plate  62  in which an electrode not shown is included is arranged on a base  64  for fixed positioning. 
         [0083]    One end of a cable  66  for supplying direct current voltage is connected to the electrode in the plastic composite plate  62 . The other end of the cable  66  is connected to a power supply  68  for outputting the direct current voltage. 
         [0084]    A charged polar character of the toner T in this exemplary embodiment is set to positive. 
         [0085]    Next, function of the third exemplary embodiment of the invention will be described. 
         [0086]    As shown in  FIG. 6A , during fixation on the recording paper  112 , the direct current voltage is not output from the power supply  68  to the electrode inside the plastic composite plate  62 , and the recording paper  112  passes between the flash fixing unit  70  and the electrostatic absorption device  60  without being absorbed. 
         [0087]    Next, as shown in  FIG. 6B , when the recording paper  112  is cut during the jam of the recording paper  112 , the jam detection device in the above-described tension roller  144  (refer to  FIG. 3 ) activates to drive the power supply  68 . 
         [0088]    By the drive of the power supply  68 , the direct current voltage is supplied to the electrode in the plastic composite plate  62 , and a surface of the plastic composite plate  62  charges negatively. 
         [0089]    Herein, as shown in  FIG. 6C , the polar character of the toner T after transferring is positive, and the polar character on a surface side of the recording paper  112 , which contacts the toner T, is negative. 
         [0090]    In addition, the polar character of the rear surface side of the recording paper  112 , which does not contact the toner T, is positive. 
         [0091]    Therefore, the recording paper  112  is drawn in an arrow E direction by a Coulomb attraction between a negative charge on the surface of the plastic composite plate  62  and a positive charge on the rear surface side of the recording paper  112 . 
         [0092]    Thereby, the recording paper  112  is kept apart from the cover glass  76 . 
         [0093]    Next, a fourth exemplary embodiment of the fixing device and the image forming device of the invention will be described with reference to the drawings. 
         [0094]    The same reference numeral as that of the above-described first exemplary embodiment is given to the basically same component as that of the above-described first exemplary embodiment, and the description thereof is omitted. 
         [0095]    As shown in  FIG. 7A , a flash fixing unit  90  is provided inside the image forming device  100  (refer to  FIG. 1 ). 
         [0096]    In the flash fixing unit  90  as one example of the fixing unit, flash lumps  92  as one example of six heat sources are arranged in a housing  91  in a box-shape having an opening on one side, and the opening is covered with a cover glass  94 . 
         [0097]    Moving units  80  are provided at positions next to right and left side surfaces of the flash fixing unit  90 . 
         [0098]    The moving unit  80  is composed of guide rails  82 , a moving plate  84 , a shaft  88 , and a solenoid  86 . 
         [0099]    A pair of the guide rails  82  set at an upper and lower positions are provided adjacent to the right and left side surfaces of the flash fixing unit  90  respectively, and the moving plate  84  is inserted between the upper and lower pair of guide rails  82 . 
         [0100]    The moving plate  84  has an abutment surface  85  abutting the recording paper  112  when detecting the jam of the recording paper  112 , and one end of the shaft  88  is fixed to a side surface opposite to the abutment surface  85  of the moving plate  84  by fitting or adhesion. Also, the other end of the shaft  88  is fixed to an axis core not shown of the solenoid  86 . 
         [0101]    In the solenoid  86 , a magnetic field generates by electric current supplied from a power supply not shown and the axis core moves in a linear line. Thereby, when the electric current is supplied to the solenoid  86 , the shaft  88  moves in a linear line, thereby the transfer plate  84  is movable along the guide rails  82 . 
         [0102]    Next, function of the fourth exemplary embodiment of the invention will be described. 
         [0103]    During the jam of the recording paper  112 , the jam detection device in the above-described tension roller  144  (refer to  FIG. 3 ) activates, and the electric current is supplied from the power supply not shown to the solenoid  86 . 
         [0104]    When the electric current is supplied to the solenoid  86 , the shaft  88  moves in an arrow F direction, and the moving plate  84  moves along the guide rails  82  in the arrow F direction. 
         [0105]    The abutment surface  85  of the transfer plate  84  presses both end portions of the recording paper  112  in an arrow G direction, and the recording paper  112  is moved from the cover glass  76 . 
         [0106]    In this manner, the recording paper  112  is kept apart from the cover glass  76 . 
         [0107]    The invention is not limited to the above-described exemplary embodiments. 
         [0108]    The fixing device  10  may be provided in a horizontal direction and an oblique direction, other than the vertical direction. 
         [0109]    The number of the flash lamps  14 ,  74  and  92  may be other than six. 
         [0110]    The number of pipes  22 ,  24 ,  44 ,  46 ,  48 ,  54  and  56  may be singular or plural and may be appropriately selected. 
         [0111]    The recording paper  112  may be kept apart from the cover glass  16  by using a cam mechanism instead of the solenoid  86 . 
         [0112]    The foregoing description of the exemplary embodiments of the present invention has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obviously, many modifications and variations will be apparent to practitioners skilled in the art. The exemplary embodiments were chosen and described in order to best explain the principles of the invention and its practical applications, thereby enabling others skilled in the art to understand the invention for various embodiments and with the various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the following claims and their equivalent