Patent Publication Number: US-2004050481-A1

Title: Method and apparatus for forming belt loops

Description:
SPECIFICATION  
       [0001] 1. Field of the Invention  
       [0002] The present invention relates generally to an image forming apparatus including an electrophotographic copier and a printer. In particular, the invention relates to forming an organic photoconductor belt.  
       [0003] 2. Background Art  
       [0004] The belt of an imaging system is formed from a web segment of at least two layers connected in a continuous band. A first layer may be of a flexible, transparent material that permits the passage of light and provides a stable platform for a second layer. The second layer is made of a photoconductive material that is placed on the first layer. The photoconductive material is adapted to attract, hold, and release toner particles.  
       [0005] To form the layers of the belt into a continuous band, a measure of the layers from a web supply roll is cut into a web (or web segment). The opposing ends of the web conventionally are wrapped to meet as a web lap joint to form a belt loop at a first location. The belt loop then is moved to a second location. At the second location, the belt loop is welded to join the web to form a looped, unitary configuration having a seam at the web lap joint.  
       [0006] The movement of the web from a first location to a second location is inefficient. The time it takes to move the web slows down production. Moreover, additional machinery required to move the web increases start up costs as well as maintenance and repair costs. Further, the additional handling of a web increases the likelihood of damaging the photosensitive layer of the web or skewing the web lap joint.  
       SUMMARY OF THE DISCLOSURE  
       [0007] A number of technical advances are achieved in the art, by implementing of an imaging system including a photoconductive belt that is wrapped and welded in a single location. The invention includes a belt forming apparatus. The belt forming apparatus includes a station, where belt wrapping and welding occur at this same station. Unlike previous arrangements for forming belts, the present invention involves welding the belt seam at the same station as where the belt is formed. Previous methods involve moving the wrapped belt material to a separate station for welding. This greatly increases the likelihood of a belt overlap becoming misaligned while shifting the belt to a separate welding station. The present invention comprises a station that includes at least one member for wrapping a belt. The wrapping member may move in a controlled translational manner. The wrapping member may also move in a controlled rotational manner. A slide (e.g. a groove or a rack-and-pinion structure) can be used to help control the wrapping movement. One embodiment includes a first invertible gripping member (e.g. a chuck), a second invertible gripping member, and a welder having a nib placed relative to the first invertible gripping member and the second invertible gripping member. The first invertible gripping member and the second invertible gripping member are adapted to wrap a web segment to form a lap joint that is disposed adjacent to the nib of the welder. Another embodiment can include simultaneous rotation and translation of wrapping members.  
       [0008] Other systems, methods, features and advantages of the invention will be or will become apparent to one with skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features, and advantages be included within this description, be within the scope of the invention, and be protected by the accompanying claims. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0009] The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. In the figures, like reference numerals designate corresponding parts throughout the different views.  
     [0010]FIG. 1 is an isometric view of a belt  100 ;  
     [0011]FIG. 2 illustrates a belt forming apparatus  200 ;  
     [0012]FIG. 3 illustrates a receiving process; and  
     [0013]FIG. 4 illustrates a wrapping and welding process.  
     [0014]FIG. 5 is a representative illustration of the surface of shoe  220 .  
     [0015]FIG. 6 illustrates a wrapping and welding process during welding.  
     [0016]FIG. 7 illustrates a wrapping and welding process after complete welding.  
    
    
     BEST MODES OF PRACTICING THE INVENTION  
     [0017] While the present invention may be embodied in many different forms, there is shown in the drawings and discussed herein a few specific embodiments with the understanding that the present disclosure is to be considered only as an exemplification of the principles of the invention and is not intended to limit the invention to the embodiments illustrated. By way of summary, the invention includes a method to wrap and weld a photoconductive belt without moving the location of the belt.  
     [0018]FIG. 1 is an isometric view of a belt  100 . Included with the belt  100  may be a web segment  102  and a seam  104 . The web segment  102  may be a divided piece of thermoplastic material from a web supply roll (not shown). The seam  104  may be formed of two ends of the web segment  102  brought together as a web lap joint and welded. The seam  104  defines a location known as the home position. The belt  100  may be a continuous band having an interior surface  106  and an exterior surface  108 . Moreover, the belt  100  may be an organic photoconductive (OPC) belt.  
     [0019] In one embodiment, the belt  100  may be made of a flexible, transparent material having a photoconductive layer. The photoconductive layer may include an organic semiconductor material such as selenium, germanium or silicon.  
     [0020]FIG. 2 illustrates a belt forming station  200 . The belt forming apparatus may be used to manufacture the belt  100  of FIG. 1. Included with the belt forming apparatus may be a cutting area (not shown). In one embodiment, the cutting area is disposed in the same location as a location of the station  200 .  
     [0021] The station  200  may be thought of as a wrapping and welding station. The cutting area may receive OPC material from a web supply roll and slice the material into individual web segments. Station  200  may include a first vacuum invertible gripping member  212 , a second invertible gripping member  214 , and a welder  216 . The description of the first vacuum invertible gripping member  212  applies equivalently to the second invertible gripping member  214 . The first invertible gripping member  212  may include a substantially round portion  218 , a planar side (“shoe”)  220 , and an axis  222 . The vacuum invertible gripping member  212  performs at least two movements, rotation and translation. Rotation entails the vacuum invertible gripping member  212  rotating upon axis  222 . Translation entails the vacuum invertible gripping member  212  moving in a plane substantially orthogonal with the axis  222 . Rotation and translation can occur simultaneously.  
     [0022] The shoe  220  may function to grab a substrate, such as web segment  102 , through a vacuum. The shoe  220  may include grooves, holes, or be made of porous, sintered particles of any suitable shape to pass a vacuum to a surface  226  of the shoe  220 , as shown in FIG. 5.  
     [0023] Referring to FIG. 2 and FIG. 6, the station  200  may include the welder  216 . The welder  216  may be an ultrasonic horn that is adapted to produce a high vibration whose frequency is sufficient to raise the temperature of the material of the web segment  102 . Referring to FIG. 2 and FIG. 6, an ultrasonic belt welding station  200  comprising an ultrasonic horn assembly  246  is illustrated. The ultrasonic horn extends or retracts in a vertical direction. The web lap joint (not shown) formed by the overlapping segment ends of thermoplastic web segment  102  is supported by the lower surface of anvil  223  and held in place above the path of ultrasonic horn assembly  246  by suction from grooves or holes  226  (see FIG. 5 and FIG. 6). The ultrasonic horn is supported by the upper end of a vertically reciprocateable shaft (not shown). The welder may be operated using a linear servomotor (not shown).  
     [0024] The welding surface (nib)  250  of the ultrasonic horn in ultrasonic horn  246  may be of any suitable shape such as the flat or curved cross-sectional shapes illustrated, for example, in U.S. Pat. No. 3,459,610 and U.S. Pat. No. 4,532,166. The high vibration frequency of the ultrasonic horn along its vertical axis causes the temperature of at least the contiguous overlapping surfaces of thermoplastic web segment  102  to increase until at least the thermoplastic material in web segment  102  flows. Welding of the contiguous overlapping surfaces of thermoplastic web segment  102  will also occur if web segment  102  also comprises thermoplastic material that flows because of the applied energy of ultrasonic oscillations. The thermoplastic web segment  102  may be coated with thermoplastic coatings. The thermoplastic material that is induced to melt and weld the seam may be provided solely by a coating on the web, from both a coating and a web substrate, or solely from the web itself. The web may be of any suitable thickness that will allow adequate heating of the contiguous overlapping surfaces of the web edges to permit sufficient heat energy to be applied at the contiguous overlapping surfaces to cause the thermoplastic material to melt and weld the overlapping edges of web segment  102  at seam  104 .  
     [0025] Any suitable heating technique may be used to provide the heat necessary at the contiguous overlapping surfaces to melt the thermoplastic material and cause it to weld web segment  102  at the lap joint  104 . Typical heating techniques include ultrasonic welding, radio frequency heating and the like. Ultrasonic welding is preferred because it causes generation of heat at the contiguous overlapping surfaces of the web edges at the lap joint to maximize melting of the thermoplastic material. If desired, the born may comprise highly thermoconductive material such as aluminum to ensure achievement of higher temperatures at the interface between the overlapping edges of web segment  102  and to minimize thermal distortion of the exposed surfaces of the web segment  102 . When ultrasonic welding is used, it is believed that the rapid impaction of one edge of web segment  112  with the other edge of web segment  110  at the contiguous overlapping web surfaces between the anvil  223  and nib  250  causes generation of heat. A horn vibration frequency of about 16,000 kHz or higher may be used to cause the thermoplastic material to soften. A typical horn suitable for joining thin thermoplastic webs uses a sonic generator of about 400-800 watt capacity, an operational frequency of about 20 kHz, and a flat input horn welding surface about 12 millimeters long and about 0.04 to 0.1 centimeter wide. Typical motion amplitude for this horn is about 76 micrometers. The horn assembly  246  moves into and out of the plane X-X of FIG. 2.  
     [0026] The rack and pinion assembly  310  may permit the first invertible gripping member  212  to rotate in the direction of the arrow  268 . Moreover, the rack and pinion assembly  310  may permit the second invertible gripping member  214  to rotate in the direction of the arrow  270 . The first invertible gripping member  212  may be disposed with a gear coaxial with the gripping member  212 . Moreover, the second invertible gripping member  214  may be disposed with a gear coaxial with the gripping member  214 . The gears rotate in communication with respective pinions to accurately control gripping member motion for translation and rotation. In one embodiment, a motor (not shown) is provided that is adapted to convert electrical power into rotational motion and translational motion.  
     [0027] The belt forming station  200  may also include auxiliary services  272 . The auxiliary services  272  may include gas  274 , fluid  276 , and electricity  278 . The gas  274  may include a gas such as air that is pressurized under a vacuum. The fluid  276  may include hydraulic fluid to rotate the apparatus parts. The electricity  278  may be coupled to motors (not shown ) that work to drive the moveable components of the belt forming station  200 . In another embodiment, a pneumatic cylinder (not shown) provides energy for rotational and translational motion. The auxiliary services  272  may be coupled to a computer  280 . The computer  280  may be any machine that may be programmed to manipulate data to perform complex and repetitive procedures through storage and retrieval of large amounts of data.  
     [0028]FIG. 3 illustrates a receiving process. As seen in FIG. 3, the station  200  is shown after the receipt of the web segment  102  from the cutting area (not shown). On receiving the web segment  102 , a vacuum may be applied to both shoe  220  and shoe  234  to draw the web segment  102  against their respective surfaces. The web segment  102  may be positioned so that web end  110  extends beyond an end of the shoe  234  and so that end  112  extends beyond an end of the shoe  220  even farther.  
     [0029]FIG. 4 illustrates an intermediate step in a wrapping and welding process. To wrap the web segment  102 , both the first invertible gripping member  212  and the second invertible gripping member  214  may be rotated about their respective axles  222 . At the same time, the first invertible gripping member  212  and the second invertible gripping member  214  may be moved towards, or away from, one another along the rack and pinion assembly  310  in the direction of the arrow  266 . In this arrangement, end  112  of the web segment  102  may be disposed over end  110 , as shown in FIG. 4. The nib  250  of the welder  216  then may be positioned to move against end  112  and the end  110  to weld the area of overlap. As shown in FIG. 6, with the nib  250  in position, the nib  250  may be activated to vibrate and moved back and forth. The ends,  110  and  112 , of the thermoplastic material of the web segment  102  may be urged to fuse and adhere together to form the seam  104  (FIG. 7).  
     [0030] The foregoing description and drawings merely explain and illustrate the invention. Those persons of skill in the art who have the present disclosure before them will be able to make modifications and variations therein without departing from the scope of the present invention. For example, the ends of the web segment  102  may be reversed so that end  110  may be disposed over end  112 . In addition, either end may extend beyond an end of either shoe  220  or  234 .