Abstract:
An article for collecting dust and debris from edges of paper rolls comprising an annular body of material having a plurality of undulations on the surface of the body to provide one plurality of ridges resiliently disposed in one direction and another plurality of ridges resiliently disposed in an opposite direction.

Description:
FIELD OF THE INVENTION 
   This invention relates in general to methods and apparatus for printing, and in particular, to a method and article for cleaning dust and debris from the edges of rolls of photographic quality print paper used in a thermal dye transfer printer. 
   BACKGROUND OF THE INVENTION 
   Digital photography is an increasingly popular form of photography. However, most photographers still want hard copies of their pictures for archival, sharing and display purposes. Conventional prints from photofinishers are far superior to most prints made from home based printers because many home based printers use conventional ink jet technology. Such conventional, ink jet printers are low cost devices and they provide printed images having a range of quality levels, some of which are unacceptable, others that fade quickly, and some that have good color and long life. Recently, thermal dye transfer printers have emerged as a consumer favorite for use in home printing of color digital images. Such printers create an image from sequential patches of different colors of donor material and apply a clear, protective coating to the finished print. These printers reproduce excellent images that are quite durable and generally superior to images made with conventional ink jet printers. 
   In a typical thermal dye transfer printer, a donor supply roller is on one side of the thermal printing head and it supplies a web of thermal dye transfer donor material. The donor web travels across a linear array of heat elements (heat line) that are selectively operated to transfer donor material from the donor web to a receiver web. The used donor web is wound on a donor take-up roller. The web of donor material may comprise a single color for monotone printing, but it preferably comprises at least three sequential sections of different colors in order to provide full-color print and a clear section for applying a protective cover on the print. 
   Beneath the print head is a cylindrical platen. The platen is coupled to a suitable drive such as a platen stepper motor by a suitable transmission such as a belt. High quality paper for receiving the dye transfer image is stored on a paper supply roll. The web of receiver paper is withdrawn from its supply roller and travels along a printing path that leads it between the platen and the donor web at the location of the print head. After transfer of the donor material, the receiver web is advanced by rollers toward a separating station where a knife separates sequential images from each other. Severed pieces of the receiver web with printed images are deposited in a discharge hopper. 
   Receiver supply rollers are normally manufactured in elongated rolls that are several feet or a meter in length or more. The long rolls are cut into smaller length rolls that fit into a typical kiosk thermal dye printing machine. The cutting action leaves a residue of unwanted particle of dust and debris that stick to the edge of the web as it is withdrawn from the roll. The sticking may be due to electrostatic, van der Waals, or other forces. Unless the particles are removed, they may jam the printer or fall onto the prints and reduce the quality of the image on the print. 
   In order to solve this problem, cleaners are typically placed along and against an edge of receiver supply rollers. The cleaners are typically made from a pliable synthetic foam material that bears gently against opposite edges of the receiver web to capture and remove dust and debris particles one the edge. Over time the cleaners accumulate more debris and dust than they can reliably hold. The cleaners must be periodically serviced and either cleaned or replaced with new cleaners. If printer operation and maintenance personnel ignore the recommended maintenance regimen, printer operation can be impaired so that it requires extensive cleaning or reconditioning. Unfortunately, this occurs with a certain degree of installed printers and is a source of manufacture warranty work that could be prevented by timely cleaning or replacement of the foam web cleaners. What is needed in the art is an automatic cleaning system for use with a thermal printer that does not itself require maintenance. 
   SUMMARY OF THE INVENTION 
   The invention provides one time use wipers for cleaning the edges of a roll of print paper installed in a printing apparatus such as a thermal dye transfer printer. In one aspect, the invention is an article for collecting dust and debris from edges of a roll of paper. In one embodiment, the wiper is an annular disk of resilient material such as paper. The disk has an inner diameter about the same size as the inner diameter of a paper roll and an outer diameter equal to or greater than the diameter of the paper roll. The paper disk version has two or more pairs of diametrically opposed creased ridges or other permanent deformations. A first set of ridges has apexes on one surface of the disk that bear against the end of a roll of paper and a second set of ridges has apexes on the other surface of the disk that bear against a flange that supports the roll of receiver paper. The paper leaves roll at a tangent to the roll and edges of the paper wipe against the ridges that face the ends of the roll. The disks are held in contact with the ends of the roll by the spring force generated by the resilient paper body of the disk and its opposing ridges. This is similar to the spring forces generated by a wavy or Bellville washer. 
   The material used for the wiper can be paper or any other material that is thin enough to fit between the ends of roll and the supporting flanges. The material should be pliable enough to form and retain ridges when the material is bent beyond its limit of elasticity. The material should also be elastic or resilient enough to generate the necessary forces for urging the apexes of the inner ridges against the end of the roll to wipe the edges of the roll as the web passes the ridges. The ridges can be creased, or not, as desired. 
   As an alternate embodiment, a wiper can be made from other materials or combinations of materials that achieve the similar results. Such other materials include and are not limited to plastic, felt, rubber and foam packaging materials of polyethylene and other natural and synthetic resilient material. Material shaped into an annular disk that is folded to provide opposing surface creased ridges is one elegant and inexpensive embodiment. Other structures could dispense with creased ridges and instead form wipers with ridges that are themselves resilient and attached to the surface of a supporting disk, or form a disk from material with ridges that are molded into the material of the disk. 
   In the one material embodiment, the wiper is placed at each end of a cylindrical roll of print paper, web or other web material that is dispensed by unrolling the web from the cylinder. Each wiper is aligned normal to the axis of the cylinder, and touches the web edge at a number of points sufficient to insure the edge of the web roll makes contact with one or more of the ridges as the web unrolls. The ridges of the wiper rub against the edges of the unrolling web, thereby engaging and removing any edge dust and debris during the unrolling process. 
   Each wiper is held by friction between one end of the rolled web and a corresponding flange that supports the roll for rotation as the receiver roller turns and its web unrolls. An edge of the receiver web thus moves across the raised creases of the wiper. While the receiver web edge is between the surface of the rolled web and the outer periphery of the wiper, the edge of the receiver web rubs against a ridge of the wiper, allowing the wiper to engage and remove dust and debris from the web edge. In all embodiments, the radius of the wiper is sufficiently larger than the maximum radius of the roll of web in order to provide adequate cleaning contact to the outermost windings of the web on the roll. 
   These and other embodiments will be understood by those skilled in the art and are shown and described in the following detailed description, the accompanying drawing and the appended claims. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  shows a several views of the receiver web at different diameters; 
       FIG. 2  shows the effective path of a point on the edge of the receiver web with respect to wiper ridges on the wiper; 
       FIG. 3  shows a schematic diagram of flanges positioned outside the receiver web with wipers on opposite sides; 
       FIG. 4  shows a schematic view of the flanges positioned to support the receiver web for rotation; 
       FIG. 5  shows one embodiment of a wiper; 
       FIG. 6  shows a schematic representation of a printer with a web of receiver sheet on a supply roller; 
       FIGS. 7A-7D  show alternate embodiments with four outer edges; and 
       FIGS. 8A-8B  show another embodiment with three outer edges. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Wiper  100  has an annular shape with an outer diameter  101  and an inner diameter  102 . The inner diameter  102  is large enough to allow passage of the boss of a flange. The paper material has a number of raised ridges  110 . 1 ,  110 . 2 , . . .  110 . n - 1 ,  110 . n , each shown in  FIG. 5  as having an optional crease. An exemplary wiper  100  is shown in  FIG. 5 . Wiper  100  is typically made of paper that is preferably stiff enough to hold a ridge. 
   In  FIG. 1  there is shown an end view of roller  27  of a receiver web  45 . Roller  27  has receiver web  45  wound on a cylinder  135  with an opening  134  along the length of its axis. When roller  27  is first installed in a printer, it has the initial diameter  130 . Receiver web  45  is drawn off roller  27  in an initial draw, shown as  45 . 1 . In  FIG. 1 , the relative position of selected ridges  110 . 1 - 110 . 4  appear as dotted radial lines.  FIG. 1  also shows roller  27  at two later times after substantial portions of receiver web  45  have been withdrawn. At such times roller  27  has a second, smaller diameter  131  and a third, still smaller diameter  132 . Receiver web  45  is tangential to roller  27  as portions of the receiver material web are withdrawn and the relative locations of receiver web  45  for the diameters are shown at  45 . 2  and  45 . 3 , respectively. When one uses a ridge, such as ridge  110 . 1 , as a reference, the path of an edge of receiver web  45  across ridge  110 . 1  describes a curved (cycloid) path across the surface of the ridges of wiper  100  (dotted arrows). To clean the edges of receiver web  45 , it would be ideal if every edge point made contact with a ridge of wiper  100  over some substantial arc of that cycloid.  FIG. 2  shows a cycloid in full (two revolutions). The contact range of a radial contact ridge  110  increases as the radius of unwinding roller  27  decreases (compare the length of the two arrows in  FIG. 1 , and the arc subtended by each arrow). 
   In a typical printer, receiver web  45  is on a roller  27  that is supported on opposite ends by flanges. For example, in the embodiment of  FIG. 3 , two flanges  125 . 1  and  125 . 2  are disposed on opposite ends of roller  27 . Flanges  125 . 1  and  125 . 2  have annular rims  124 . 1 ,  124 . 2  that extend from axial bosses  126 . 1 ,  126 . 2 , respectively. The outside diameters  122 . 1 ,  122 . 2  of rims  124 . 1  and  124 . 2  is preferably the same diameter or greater than the outside diameter of roller  27 . The outside diameter of wipers  100 . 1  and  100 . 2  is also equal to or greater than the outside diameter of roller  27 . Wipers  100 . 1  and  100 . 2  are positioned adjacent the opposite ends of receiver web  45  and between flanges  125 . 1  and  125 . 2  and ends of roller  27 . Bosses  126 . 1 ,  126 . 2  are tapered to limit the penetration of the bosses into axial opening  134  of the web support cylinder  135 .  FIG. 4  shows wipers  100 . 1 ,  100 . 2 , respectively, between flanges  125 . 1 ,  125 . 2 , respectively and roller  27  of receiver web  45 . 
   Turning to  FIG. 6 , there is shown a schematic of a thermal printer  10  that may benefit from the invention. Printer  10  has a donor supply roller  26  that supports a donor web  35  of thermal transfer donor material. Donor web  35  extends along a path that includes the donor supply roller  26 , a first idler roller  25 , a first stripping plate  24 , thermal print head  23 , a second stripping plate  22 , a second idler roller  21  and donor take-up roller  20 . 
   Roller  27  of receiver web  45  is located in printer  10 . The view in  FIG. 6  omits flanges and wipers so that the operation of printer  10  may be explained. Receiver web  45  can be any suitable material, cloth or paper including but not limited to special paper for receiving thermal dye transfer images of digital photographs. Receiver web  45  travels back and forth along a paper path  5  that includes a pair of forward drive rollers  30 , a freely rotating support platen roller  29 , and a pair of reverse drive rollers  28 . Print head  23  engages the donor and receiver webs  35 ,  45 , friction between the two webs is strong enough for the drive rollers  30 ,  28  to move the two webs together past the print head  23 . Drive rollers  30  have relatively powerful motors or gear trains that provide high enough torque to move the webs  35 ,  45 . In contrast, torque applied to supply and take-up rollers  26 ,  20  is just enough to prevent slack in donor web  35 . In operation, forward drive rollers  30  pull donor and receiver webs  35 ,  45  from right to left and drive rollers  28  pull donor and receiver webs  35 ,  45  in the opposite direction. Donor web  35  passes over and contacts print head  23 . Receiver web  45  is disposed between donor web  35  and a free turning platen roller  29 . Rollers  20 ,  26  and  27  have suitable drive motors (not shown) and/or drive trains for turning rollers  20 ,  26 ,  27  in clockwise or counterclockwise directions to accommodate driving donor and receiver webs  35 ,  45  in forward and reverse directions. 
   Printer  10  has suitable circuits, sensors, integrated circuits, processors, memory, operating and application software, for operating and controlling printer  10  and the individual components thereof. In particular, a controller  60  raises and lowers print head  23 , selectively operates the heater elements in the print head  23  that transfer donor material from donor web  35  to receiver web  45 , operates drive rollers  28 ,  30  to move receiver web  45  in the forward (right to left) and reverse (left to right) directions, operates the supply and take-up rollers  26 ,  20  to move donor web  35  in forward or reverse directions. Controller  60  has lines  61  and  65  that that connect controller  60  with sensors and actuators at the supply and take-up rollers  26 ,  20 . Other lines  62 ,  64  connect controller  60  to actuators (not shown) for drive rollers  30 ,  28 . Line  63  connects controller  60  to print head  23  and carries signals for actuators (not shown) that raise and lower print head  23  and also selectively operate the heating elements in print head  23 . Another line  66  connects controller  60  to an actuator (not shown) for receiver web roller  27 . 
   Those skilled in the art understand that the schematic of  FIG. 6  omits details of the controls for operating printer  10 . However, these controls are generally conventional and may be found in other machines and are otherwise well-known to those skilled in the art. Likewise, this description omits the motors, solenoids and other actuators, sensors and encoders that are used for turning and driving supply and take-up rollers  26 ,  20 , drive rollers  30 ,  28  and receiver roller  27 . Again, those items are well-known to those skilled in the art. Also known to those skilled in the art are suitable electronics for actuating the heater elements in a linear array of a thermal print head. Those skilled in the art further understand that thermal print head  23  and platen roller  29  are kept in close engagement during printing. A linear actuator (not shown) moves print head  23  relative to platen roller  29  in order to permit donor web  35  to index from one color section to another. 
   In operation, receiver web  45  is withdrawn from roller  27 . Roller  27 , its wipers  100 . 1 ,  100 . 2  and its flanges  125 . 1 ,  125 . 2  turn together. However, as receiver web  45  separates from roller  27 , the edges of receiver web  45  wipe against the raised ridges  110 . 1 - 110 . n  of wipers  100 . 1 ,  100 . 2 . The raised ridges remove dust, debris and other spurious materials from the edges of receiver web  45 . When all of receiver web  45  on roller  27  is expended, it is removed from printer  10 , and flanges  125 . 1 ,  125 . 2  are separated, and roller  27  and wipers  100 . 1 ,  100 . 2  are discarded. A fresh roller  27  is selected. In the one embodiment, each roller  27  is packaged together with a pair of fresh wipers  100 . 1 ,  100 . 2 . The operator is thus encouraged by the common packaging of wipers  100 . 1 ,  100 . 2  and roller  27  to install new wipers  100 . 1 ,  100 . 2  with each new roller  27 . This provides fresh, clean wipers for each new roll. 
   The above embodiment disclosed that wipers  100 . 1  and  100 . 2  that are made from inexpensive paper material that has raised radial contact ridges in the cleaning material to make effective contact with the edges of receiver web  45 . As should be made clear from  FIG. 1 , this constraint requires either that wipers  100 . 1  and  100 . 2  make effective contact with the edge at all points on its surface, or that the wipers  100 . 1  and  100 . 2  make effective contact with an edge of receiver web  45  at a sufficient number of points to ensure that many or all points on receiver web  45  are effectively cleaned. The interval between radial contact ridges must be kept small enough to insure complete cleaning. 
   Those skilled in the art understand that other embodiments of the invention are possible. For example, in a very simple form, a simple annular disk of paper could be folded in half and then into quarters to provide a minimal set of creased ridges. Other embodiments include annular disks made of synthetic, resilient material with ridges of the same or different material embedded into the faces of the annular disks. Such embodiments would use material with an elastic consistency to ensure uniform surface contact at all points of the web edge. Those skilled in the art also understand that annular wipers or disks may be made of any suitable material including and not limited to paper, plastic, felt, rubber and foam packaging materials of polyethylene and other natural and synthetic resilient material. 
   In addition, the invention is not limited to annular disks with circular outer diameters. Embodiments of the invention may be fashioned from paper with any outer border, including and not limited to square or rectangular outer borders. The outer border may be any border configuration including and not limited to regular and irregular or amorphous shapes, circular, and regular polygon and irregular polygon. Two further examples are show. 
   The first further example is a regular polygon in the shape of a square. See  FIGS. 7A and 7B . Wiper  170  is shown against the phantom view of first receiver diameter  130  of the outer diameter of the receiver roller. There are four, optionally creased, ridges  171 . 1 - 171 . 4 . Note also the quadrilateral opening  172 . When the wiper  170  is folded across two diagonally opposite creased ridges  171 . 1 ,  171 . 3 , it has a trapezoidal profile as seen in  FIG. 7B . Another four-sided embodiment is shown in  FIG. 7C . There the wiper  176  has four creased ridges  175 . 1 - 175 . 4  and a circular opening  178 . It profile ( FIG. 7D ) is quasi-trapezoidal with an arch-like apex  178  that becomes a circular opening when placed against the side of the receiver roller  27 . As such, the annular body of the invention may have outer and inner borders that are circular or defined by a polygon of regular or irregular edges or by combinations of circular and polygon edges. In particular, and as shown in  FIGS. 7A-7D , the invention may have a quadrilateral outer and inner borders or a quadrilateral outer border and a circular inner border. The quadrilateral may be in the shape of a rectangle or square. 
   A second further example is a regular polygon with three sides. See  FIGS. 8A and 8B . They show a three sided wiper  180 . It has a three sided outer border  182  and an inner opening  183  also defined by a three sided inner border  184 . First outside ridges  186 . 1 ,  186 . 2  and  186 . 3  are optionally creased and extend from inner border  182  to the apexes of the outer border. Second inside ridges  185 . 1 ,  185 . 2  and  185 . 3  are also shown as being optionally creased and extend from about the midpoints of the outer and inner sides. 
   Thus a wiper may have any suitable outer border shape and any suitable inner border shape. If made of paper or other deformable and resilient material, the material is permanently creased into wiper ridges. The wiper ridges bear against the ends of the receiver roller. The wiper may be self-biasing by providing creases on both sides in a manner similar to wavy or Bellville washers. The creased ridges provide the bias and the wiping edge that removes dust and debris from the edges of the receiver roller. 
   The invention has been described in detail with particular reference to certain preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention. 
   PARTS LIST 
   
       
       5 paper path 
       10 printer 
       20 donor take up roller 
       21 idler roller 
       22 strip plate 
       23 thermal print head 
       24 strip plate 
       25 idler roller 
       26 donor supply roller 
       27 receiver roller 
       28 drive roller 
       29 platen roller 
       30 drive roller 
       35 donor web 
       45 receiver web 
       45.1 first tangent 
       45.2 second tangent 
       45.3 third tangent 
       60 controller 
       61 control line 
       62 control line 
       63 control line 
       64 control line 
       65 control line 
       66 control line 
       100 wiper 
       100.1, 100.2 wiper 
       101 o. d. wiper 
       101.1, 101.2 o. d. wiper 
       102 i. d. wiper 
       110 ridges 
       110.1, 110.2 ridges 
       110.n, 110.n-1 ridges 
       122.1, 122.2 o. d. flange 
       124.1, 124.2 rim 
       125.1, 125.2 flange 
       126.1, 126.2 boss 
       130 first receiver diameter 
       131 second receiver diameter 
       132 third receiver diameter 
       134 opening 
       135 support cylinder 
       170 four-sided wiper 
       171.1 creased ridge 
       171.2 creased ridge 
       171.3 creased ridge 
       171.4 creased ridge 
       172 opening 
       175.1 creased ridge 
       175.2 creased ridge 
       175.3 creased ridge 
       175.4 creased ridge 
       176 four-sided wiper 
       178 opening 
       180 three-sided wiper 
       182 outer border 
       183 inner opening 
       184 inner border 
       185.1 inside ridge 
       185.2 inside ridge 
       185.3 inside ridge 
       186.1 outside ridge 
       186.2 outside ridge 
       186.3 outside ridge