Abstract:
A portable, compact electronic device is disclosed which is adapted for communication with a personal digital assistant. The electronic device includes a housing having an opening adapted for receiving a medium adapted for printing or scanning and at least one coiled structure formed from a coilable material. At least one guide positions the coilable material as it is extended from the coiled structure. The printing or scanning medium is moved through an opening in the housing by rotating elements. An activation means is utilized to perform printing or scanning of the medium, under the controlled extension and retraction of the coilable material from the coiled structure.

Description:
INCORPORATION BY REFERENCE  
       [0001]    The following U.S. patents are fully incorporated herein by reference: U.S. Pat. No. 6,208,427 to Lee (“Personal Digital Assistant (PDA) Printer Apparatus and Printing Method”); U.S. Pat. No. 6,392,674 to Huggins et al. (“Portable Printer”); and U.S. Pat. No. 6,367,993 to Day et al. (“Printer System”). 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    This invention relates generally to printers, and more particularly to portable printers that may be used with a personal digital assistant.  
           [0003]    A number of portable printers for use with computers or other electronic devices are known in the art. For example, U.S. Pat. No. 6,367,993 to Day et al. for a “Printer System” teaches a portable printer which resides in a base station connected to a computer when not in use. When it is desired to execute a printing application, the printer is removed from the base station and is manually placed on a print medium to initiate printing. Print alignment is achieved visually through a transparent window in the printer casing. The window may also be opened for inserting an ink cartridge into the printer before use.  
           [0004]    A lightweight, portable printer for the production of labels is described in U.S. Pat. No. 6,394,674 to Huggins et al. for a “Portable Printer”. Huggins teaches a battery-operated unit into which label supplies are loaded for printing. In this case the printing medium is fed through the printer rather than the printer being placed on the printing medium. The printer housing contains a motor-driven print head, a platen roll and gear, a holder for a supply roll of labels, a battery compartment, and various other features.  
           [0005]    In contrast to this approach, U.S. Pat. No. 6,208,427 to Lee for a “Personal Digital Assistant (PDA) Printer Apparatus and Printing Method” teaches a PDA printer which is able to output a note without a header, as if the note were printed by a printer. In a conventional PDA, a note is printed by direct connection to a printer or by using a fax transmission. However, the former method requires a driver program for driving the printer, which results in development constraints upon the driver program and portable printer. As a result, fax transmission is generally used. To achieve a printing method in which a fax transmission function is improved by outputting a note without a header, the Lee device provides a display, a fax modem memory, and a method for printing a fax transmission without a header.  
         SUMMARY OF THE INVENTION  
         [0006]    Briefly stated, and in accordance with one aspect of the present invention, there is disclosed a portable, compact electronic device which is adapted for communication with a personal digital assistant. The electronic device includes a housing having an opening adapted for receiving a medium adapted for printing or scanning and at least one coiled structure formed from a coilable material. At least one guide positions the coilable material as it is extended from the coiled structure. The printing or scanning medium is moved through an opening in the housing by rotating elements. An activation means is utilized to perform printing or scanning of the medium, under the controlled extension and retraction of the coilable material from the coiled structure. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]    The foregoing and other features of the instant invention will be apparent and easily understood from a further reading of the specification, claims and by reference to the accompanying drawings in which:  
         [0008]    [0008]FIG. 1 illustrates a top view of the operational concept of a double spool embodiment of the subject invention;  
         [0009]    [0009]FIG. 2 illustrates a more detailed top view of a double spool embodiment of the subject invention;  
         [0010]    [0010]FIG. 3 illustrates a side view of the embodiment of FIG. 2;  
         [0011]    [0011]FIG. 4 illustrates a side view of an alternate double spool embodiment of the subject invention;  
         [0012]    [0012]FIG. 5 illustrates an operational side view of the double spool embodiment of FIG. 4;  
         [0013]    [0013]FIG. 6 illustrates a top view of the print head of the subject invention as it moves across the print medium;  
         [0014]    [0014]FIG. 7 illustrates a side view of an alternate double spool embodiment of the subject invention;  
         [0015]    [0015]FIG. 8 illustrates a top view of the embodiment of FIG. 7;  
         [0016]    [0016]FIG. 9 illustrates possible skew of the print head as it moves across the print medium;  
         [0017]    [0017]FIG. 10 illustrates a piggyback actuator that adjusts the print head position of an embodiment of the subject invention;  
         [0018]    [0018]FIG. 11 illustrates a printing path adjustment to correct for possible skew of the print head as it moves across the print medium;  
         [0019]    [0019]FIG. 12 illustrates a top view of a single spool embodiment of the subject invention;  
         [0020]    [0020]FIG. 13 illustrates a side view of the embodiment of FIG. 12;  
         [0021]    [0021]FIG. 14 illustrates another single spool embodiment of the subject invention;  
         [0022]    [0022]FIG. 15 illustrates the operation of the embodiment of FIG. 15;  
         [0023]    [0023]FIG. 16 illustrates another embodiment of the subject invention; and  
         [0024]    [0024]FIG. 17 illustrates use of a motor to control winding and unwinding of the spool of the subject invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0025]    The portable coilable device disclosed herein operates as a printer or scanner attachment to various electronic devices, such as the palm pilot personal digital assistant (PDA), among others. One requirement for such devices is that their physical size not be limited by the size of the print medium. For example, the majority of home/office printers and scanners currently on the market have at least one dimension longer than the 8.5 inches required for printing or scanning a portrait letter size page. In the following discussion, the subject coilable device will be described in terms of a printer, however, the coilable device could also be beneficially employed as a scanner as well as in other electronic applications, all of which are fully contemplated by the specification and the breadth of the claims herein.  
         [0026]    Turning now to FIG. 1, there is illustrated a top view of the operational concept of a double spool embodiment of the subject invention as well as an example cross-sectional configuration. Any coilable material which can deform and coil around a spool without being permanently deformed is contemplated for fabrication of the coilable arm. For example, the coilable material may be formed of a resilient metallic ribbon having a concavo-convex cross-section coiled in an internal or “inside wound” fashion. To this substrate kapton and/or copper may be laminated to form multiple conductors along the coil. Slip contacts at the center of the spool may be utilized to carry electrical power and signals to external circuits. The coilable material is coiled against the inner periphery of an annular surface and, when the leading end of the tape is laterally displaced from the coil, the tape will automatically uncoil into a straightened, relatively stiff configuration without the necessity of a separate spring. This structure is wound onto two spools  110  when the printer is not in operation and is extended through guides  120  to form an extendable cantilever printer arm when printing is to be initiated. This configuration provides good bending stiffness in all directions, resistance to buckling, and a relatively low printer profile. Printer arm  130  may have various cross-sectional configurations, for example two facing arcs or two opposed arcs  150  and  160  as shown in cross-section  140 . However, it will be appreciated by one skilled in the art that other cross-sectional configurations could be similarly beneficially employed. The example configurations allow the weakest bending stiffness of one of the arm extensions to be compensated by the other opposed arm extension, resulting in a cantilever arm that is reasonably stiff and is resistant to buckling. Additionally, this configuration provides a form factor with a low profile, since spools  110  lie flat, thus permitting a thin design for the portable printer.  
         [0027]    Referring now to FIG. 2, there is shown a top view of one embodiment of the subject invention. Here the portable printer  220  is attached as a modular unit to PDA  210 . Paper  275  is driven by rotating elements  230  through a slot underneath the coilable structures  270 , which have extended through guides  240  as printer arm  280 , carrying print or scanner head  250  in a direction traverse to the direction of movement of paper  275 . Equally spaced rectangular marks may be printed along the length of the coilable material. Such marks, in conjunction with an optical emitter and sensor, may be used to measure the amount of coiled material being extended out from rotating elements  230 . This position signal may then be used in feedback control of position and velocity by rotating elements  230 . Rotating element  260  maintains a constant distance between printer or scanner head  250  and paper  275  as well as supporting the head of the printer or scanner. The print head may also be extended beyond the outer edge of paper  275  such that rotating element  260  moves off the paper&#39;s edge, at which position the paper can be advanced, as indicated by arrows  290 . Both coilable structures  270  are mounted within printer  220  in a plane parallel to the plane of paper  275 . The core of coilable structures  270  may also include a motor controlling extension and retraction of the coiled material. Alternatively, a preloaded spring in the core of coilable structures  270  may be utilized to maintain the coiled configuration of the coilable structures.  
         [0028]    A side view of this embodiment is illustrated in FIG. 3, where housing  310  includes slot  320 , through which paper  370  moves when the print head is in operation. As can be seen in the figure, rotating element  330  contacts paper  370  in the slot to cause movement of paper  370 . Printer arm  380  is in an extended position along which print head  350  may move as it is supported by roller  360 . To initiate printing, a user inserts the left, top corner of paper  370  up from below lower roller  330 , with paper  370  placed against the inner edge of slot  320 . The user then initiates a start command from the PDA, causing roller  330  to rotate and draw paper  370  towards print head  350 . An optical detector inside slot  320  may be utilized to identify the top edge of paper  370  and advance the paper to the start position for printing. The coilable printer arm  380  is then extended along the width of paper  370  and ink is deposited in each pixel location traversed by print head  350 .  
         [0029]    Turning now to FIGS. 4 and 5, a partial illustration of an alternate embodiment of the subject invention is shown. In this embodiment, print head  470 , supported by rotating element  480 , moves along printer arm  460  across paper  450 . In this figure, only the bottom portion of housing  410  is illustrated, with paper  450  moving through slot  420 . Coilable structures  440  are supported by hinge structure  430  having hinge point  435 . However, in this embodiment, ramp  490  permits the print head&#39;s rotating element to unload from paper  450  when the cantilever arm is fully retracted, as shown in FIG. 5. An optional locking mechanism (not shown) or housing structure (not shown) may be included to retain the rotating element in its retracted position when the printer is not in use. When rotating element  480  unloads from paper  450 , a pair of rotating elements  415  in slot  420  continue to advance paper  450 . As can be seen in FIG. 5, as rotating element  580  moves along ramp  590  with print head  570 , hinge structure  530  rotates about hinge point  590  to continue to support coilable structures  540  when print head  570  is in a retracted position, while rolling elements  515  continue to advance paper  550 .  
         [0030]    The position of the print head relative to the print medium is illustrated in FIG. 6. Here partially-represented housing  610  contains rotating elements  620 , which are capable of moving paper  680  from a page top position to a page bottom position. Print head  630 , supported by rotating element  640 , moves across paper  680  from retracted position “a” to a partially advanced position “b” and finally to a fully advanced position “c”. In position “b” paper  680  cannot be advanced by rotating elements  620 . However in positions “a” and “c” paper  680  is free to be moved up or down. Also, in this embodiment it should be noted that rotating element  640  is positioned relative to print head  630  such that rotating element  640  does not contact ink recently deposited on paper  680 .  
         [0031]    [0031]FIG. 7 illustrates a side view of yet another embodiment of the subject invention. Here additional rotating elements  720  are placed between PDA  790  and printer  710  so as to support and carry both PDA  790  and printer  710 . Rotating elements  720  are beneficially employed in those situations in which the size of page  750  is so large that driving rotating elements  730  would tend to skew page  750  as it moves through slot  740 . In this embodiment, paper  750  remains stationary while the printer moves relative to the paper after printer arm  780  has extended sufficiently for print head  760  and rotating element  770  to clear the outside edge of paper  750 .  
         [0032]    A top view of this configuration is shown in FIG. 8. Here the PDA attached to printer  810  is in operating position midway down paper  870 . Rotating elements  820  support printer  810  as it moves down paper  870  while print head  850  supported by rolling spherical element  860  moves back and forth across paper  870  on printer arm  840  from a first position “a” to a second position “b”. Rotating elements  830  move in the same direction as rotating elements  820  to advance paper  870  relative to the PDA. Since the PDA also moves relative to the surface on which it is positioned, the two motions cancel each other and result in the movement of printer  810  but not paper  870 .  
         [0033]    Turning now to FIG. 9, there is illustrated a possible skew of the printer arm to either position  920  “a” or  920  “b”, causing print head  930  to be displaced on paper  940  during printing. This may be corrected as shown in FIG. 10, in which printer housing  1010  is partially illustrated. Here laser emitter  1020  is installed in the printer housing (shown in a top view) and a linear optical sensor  1060  may be installed in print head  1050  (shown in side view) to measure the deviation. In operation, a laser beam emitted from laser emitter  1020  from a source on the stationary side of printer housing  1010  is detected by a row of optical sensors  1060 . The row of sensors may typically be comprised of tens to over a hundred individual optical sensors spaced from each other. The reflecting surface above sensors  1060  ensures that over a certain range of paper length variations the laser beam can still be directed onto the sensors. If print head  1050  deviates up or down as it is traversing left and right, the laser beam will shine on different portions of the row of optical sensors. The detected deviation may then be compensated for mechanically by having the printer head carried by actuator  1030  which shuttles the printer head through use of gears  1040  by the same amount of deviation in the opposite direction.  
         [0034]    Alternatively, computing and then altering the ink pattern that comes out of unshuttled jets can correct the positional deviations, as illustrated in FIG. 11. This figure illustrates the ink deposition pattern for ink emitters in a print head as it moves across a sheet of paper depositing pixels of ink. In this example, print band  1110  has upper bound “a” and lower bound “b” when the actual print head path  1150  deviates from a straight path and is detected by the laser sensor. Ink emitters in the print head are reprogrammed to emit ink at droplet locations  1130  or partially emit ink at droplet locations  1140  within desired print band  1110 . For those droplet locations outside of print band  1110 , no ink is deposited, as shown at positions  1120 .  
         [0035]    Turning now to FIG. 12, there is shown another embodiment of the subject invention in a top view. As is the case with the above embodiments, the portable printer may be a modular attachment to a PDA or other electronic device. Here a single coiled material is utilized rather than two opposed coils. In this case lateral bending stiffness is enhanced through optimization of material specification and geometry. A requirement of the printer arm is that is should not deviate from the orthogonal direction at any position of its extension. Considering the accuracy requirement of a 600 dpi printer, a deviation of a few dots in the forward or reverse directions, which would be less than 200 microns, could result in unacceptable print quality. To correct for positional deviations, a laser guidance method is described hereinabove. Alternatively, a single spool implementation, such as that shown in FIG. 12, could minimize positional deviation to an acceptable amount without use of a laser subsystem.  
         [0036]    In this example embodiment, portable printer  1200  includes housing  1210  and a slot (not shown) through which paper  1270  is driven by rotating elements  1220 . Coilable structure  1260  extends and carries a print head  1240  from position “a” to position “b” in a direction traverse to the movement of paper  1270  through the printer slot. Rotating element  1250  maintains a constant distance between print head  1240  and paper  1270  while supporting print head  1240 . Although print head  1240  at position “b” is shown as being positioned on paper  1270 , print head  1240  may also be extended beyond the outer edge of paper  1270 , at which position rotating element  1250  moves off the edge of paper  1270 . In this furthest advanced position of print head  1240 , paper  1270  may be advanced through the printer slot.  
         [0037]    Referring now to FIG. 13, which shows a side view of the embodiment of FIG. 13, coilable structure  1320  resides in housing  1310  and extends outward to carry print head  1360  supported by rotating element  1370  in a transverse direction on paper  1380 . In this embodiment, an optional second structure  1330  may be present to feed signal and power cables between the printer body and print head  1360 . Both coilable structure  1320  and coilable signal structure  1330  are mounted within housing  1310  in a plane orthogonal to the plane of paper  1380 . Although in this example embodiment coilable structure  1320  and coilable signal structure  1330  are illustrated as separate structures, the two may be combined into a single structure. In this example, signal and power lines can be laminated into the load-bearing coilable structure.  
         [0038]    Turning now to FIGS. 14 and 15, an alternate embodiment is illustrated. Here housing  1410 , partially shown, includes ramp  1420 , such that rotating element  1470  of print head  1460  will unload from paper  1440  when cantilever arm  1480  is fully retracted into coiled structure  1450 . When rotating element  1470  unloads from paper  1440 , a pair of rotating elements (not shown) in slot  1430  can advance paper  1440 . Paper  1440  is positioned to move through slot  1430 . FIG. 15 illustrates the relative positions of the coilable structure  1550  within housing  1510  (partially shown) and the print head when the print head is moving into a fully retracted position. As can be seen, as rotating element  1570  moves along ramp  1520  supporting print head  1560 , coilable material extended from coiled structure  1550  flexes slightly at point  1580  as print head  1560  moves up ramp  1520  into a retracted position. At this position paper  1540  may be removed from slot  1530 .  
         [0039]    Referring to FIG. 16, another embodiment of the coilable structure utilizes driving gears  1610  and  1620  opposing each other on opposite sides of uncoiled structure  1650 . In this embodiment, teeth are formed into the extending edges of the coilable structure to facilitate coupling gears to the driving motor. With this approach slippage, which can cause lateral deviation of print head  1630 , is minimized. In those embodiments in which a preloaded spring maintains the wound condition of the coilable structures, an actuator driving gears which mesh with teeth on the coiled material of the coiled structures provides the force needed to pull the coiled material into an uncoiled state and then return the material to the coiled state. Alternatively, instead of a preloaded spring, a motor may be placed in the core of the coilable structures to wind and unwind the coiled material. This approach is illustrated in FIG. 17, in which motor  1710  rotates at a variable ratio to motor  1720  depending on how much of coiled material  1740  remains in coiled structure  1750  to minimize drag on the movement of coiled material  1740  through gears  1730 .  
         [0040]    While the present invention has been illustrated and described with reference to specific embodiments, further modification and improvements will occur to those skilled in the art. It is to be understood, therefore, that this invention is not limited to the particular forms illustrated and that it is intended in the appended claims to embrace all alternatives, modifications, and variations which do not depart from the spirit and scope of this invention.