Abstract:
An apparatus comprising a transfer roller for transferring an image to a print medium, a laminating device to substantially cover the print medium with a laminating powder, and a pressing roller to press and substantially affix the image and the laminating powder to the print medium.

Description:
TECHNICAL FIELD  
         [0001]    The present invention relates generally to the field of printing devices. More particularly, the present invention relates to an apparatus and method for laminating a print medium in a printer.  
         BACKGROUND OF THE INVENTION  
         [0002]    Laser printers, copiers, and other similar printing devices mainly include: a photosensitive drum, a developing roller, and a transfer roller or corona wires. In general, in such printing devices, an image is created on the photosensitive drum and then transferred to a sheet of print medium. As used herein, and in the appended claims, the terms “printing device” or “printer” will be understood to refer to all such devices that output a hardcopy document based on the transfer of an image to a sheet of print medium.  
           [0003]    [0003]FIG. 1 demonstrates a typical laser-printing device. In a typical printing device, a charging device or corona wire  112  uniformly applies an electrical charge to the outer peripheral surface of a photosensitive drum  120 . A laser-generating unit  114  modulates a laser beam  110  based on data defining the image to be printed. The modulated laser beam  110  is then scanned across the outer peripheral surface of the photosensitive drum  120 . As a result, a corresponding electrostatic latent image is formed on the surface of the photosensitive drum  120  in the charge pattern.  
           [0004]    The developing cylinder  116  conveys, on its surface, toner that is electrically charged to the same polarity as that of the charge on the photosensitive drum  120 . Consequently, the photosensitive drum  120  repels the toner, except where the latent image has been written into the charges on the drum. The electrostatic latent image on the photosensitive drum is thus developed into a visible toner image by the toner supplied from the developer cylinder  116 .  
           [0005]    The developed visible image is then transferred from the photosensitive drum  120  onto a sheet of paper, or other print medium, passing between the photosensitive drum  120  and the transfer roller  122 . The transfer roller  122  or corona wires (not shown) transfer a static charge to each sheet of print medium. This charge, in turn, attracts the toner from the photosensitive drum  120  to the print medium causing the image to be transferred to the print medium under pressure from the transfer roller  122 .  
           [0006]    Once the visible image is on the print medium, the print medium passes through a designated transport path  124  to a fuser  111 . When the print medium reaches the fuser  111 , it heats the print medium causing the toner to partially melt and stick to the print medium forming a substantially permanent bond.  
           [0007]    A number of common applications also call for a protective sheet to cover the printed medium in order to protect the printed medium as well as strengthen and prolong medium life. Traditionally, lamination has served this purpose. A traditional method for laminating a printed medium calls for the printed medium to be removed from the location of the printer and transported to an external laminating device. Once at the lamination device, a pair of lamination sheet members are placed over the printed medium, top and bottom, and pressed at relatively high temperatures to hermetically seal the printed medium.  
           [0008]    While traditional methods of laminating printed medium are effective in protecting the printed medium, a number of disadvantages are inherent in traditional methods. Traditional methods require a separate machine to perform the lamination. The use of an extra machine increases the overall cost of the process as well as consumes valuable space. Moreover, the traditional method of laminating requires the additional steps of transporting the printed medium to the laminating device, placing the medium between the lamination sheet members and placing the medium in the laminating device to receive an application of heat and pressure. These additional steps increase both process time and labor.  
           [0009]    Efforts have been made to address the shortcomings of traditional laminating methods as demonstrated by U.S. Pat. No. 5,878,303 issued to Endo and by U.S. Pat. Nos. 5,807,461 and 6,022,429 issued to Hagstrom. These efforts have focused on incorporating the use of conventional lamination sheet members in the printing process. FIG. 2 illustrates the current state of the art. Similar to traditional laser printers, a toner-based image is transferred from a photosensitive drum  220  to a print medium. Once the image is transferred to the print medium by the transfer roller  222 , laminate sheet members  234  are used to hermetically seal the print medium. In order to surround the print medium, a laminate sheet transport system  230  is implemented immediately after the transfer roller  222 . The laminate sheet transport system  230  is made of a transport web  232  which supplies the lamination sheet members  234  to surround the print medium, introduces the print medium between the lamination sheet members  234 , and transports the surrounded print medium to the fuser  211  where the lamination sheet members  234  are sealed to the print medium.  
           [0010]    While the above-mentioned solutions do allow both printing and lamination of print medium in a single machine, the process sacrifices space by greatly increasing the overall size of the printing device. Additionally, the process increases the complexity of the printing machines by having to address the regulation of the bias voltage of the transfer roller  222  to prevent residual toner located on the drum  220  and the roller  222  from transferring onto and marking the lamination sheet members  234 .  
         SUMMARY OF THE INVENTION  
         [0011]    In one of many possible embodiments of the present invention, a printing apparatus includes a transfer roller for transferring an image to a print medium, a laminating device for substantially covering the print medium with a laminating powder, and a pressing roller to press the print medium after receipt of the image and the laminating powder in order to substantially affix the image and the laminating powder to the print medium. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]    The accompanying drawings illustrate embodiments of the present invention and are a part of the specification. Together with the following description, the drawings demonstrate and explain the principles of the present invention. The illustrated embodiments are examples of the present invention and do not limit the scope of the invention. Like reference numerals refer to similar, though not necessarily identical, elements in the figures of the accompanying drawings.  
         [0013]    [0013]FIG. 1 shows a perspective view of a prior art laser printer design.  
         [0014]    [0014]FIG. 2 illustrates a perspective view of a prior art laser printer design that includes the use of laminating sheet members.  
         [0015]    [0015]FIG. 3 demonstrates a printing device according to an embodiment of the present invention.  
         [0016]    [0016]FIG. 4 illustrates a perspective view of a laminating device according to an embodiment of the present invention.  
         [0017]    [0017]FIG. 5 demonstrates an alternative embodiment of a printing device according to principles of the present invention.  
         [0018]    [0018]FIG. 6 demonstrates an alternative embodiment of a printing device according to principles of the present invention.  
         [0019]    [0019]FIG. 7 demonstrates a printer control executed in the control unit according to an embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0020]    Embodiments of the invention are generally drawn to an apparatus for creating laminated output directly from a printing device. According to one example implementation, described more fully below, an innovative printing device is presented that outputs laminated documents. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the invention. It will be apparent, however, to one skilled in the art that the invention can be practiced without these specific details.  
         [0021]    Reference in the specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. The appearances of the phrase “in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment.  
         [0022]    Exemplary Overall Structure  
         [0023]    [0023]FIG. 3 illustrates an embodiment of a printing device according to principles of the present invention. As shown in FIG. 3, such a printing device preferably includes a corona wire  312  in substantially close proximity to a photosensitive drum  320 . A laser-scanning unit  314 , a developer cylinder  316 , a toner supply  318 , and a transfer roller cylinder  322  are also located adjacent to the photosensitive drum  320 . Some of these components are located in or along a print medium transport path  324 . Moving along the direction of the transport path, immediately after the transfer roller cylinder  322  is a laminate applicator  332  and a laminate transfer roller  323 . Subsequent to the laminate transfer roller  323  the transport path  324  for print media extends to a fuser  311 . FIG. 3 also illustrates a controller  308  communicatively coupled to the laser-scanning unit  314 , the photosensitive drum  320 , and the fuser  311 . Throughout the operation of the present invention, the controller  308  controls the function of the laser-scanning unit  314 , the photosensitive drum  320 , and the fuser  311 .  
         [0024]    The laminate applicator  332  preferably applies a laminating powder to the printed sheet of print media. When exposed to the heat of the fuser  311 , the laminating powder melts into a clear layer of lamination that covers and seals the printed sheet. Preferably, the laminating powder is a polarized polymer powder that melts and substantially bonds with the print medium when heated.  
         [0025]    Alternative embodiments of the present invention are also demonstrated in FIGS. 5 and 6. FIG. 5 demonstrates an alternative embodiment of the present invention that incorporates two laminate applicators  332  with the laminator cylinders  344  coupled. FIG. 6 illustrates an embodiment of a printing device that selectively applies laminating powder to a print medium. As shown in FIG. 6, the printing device preferably includes two photosensitive drums  320 : one in communication with a toner supply  318  and developer cylinder  316 , and one in communication with a laminate applicator  332  and a laminate powder reservoir  342 . In the embodiment illustrated in FIG. 6, each photosensitive drum  320  is also in communication with a roller  322 ,  323  and a corona wire  312 . A transport path  324  is located after the second photosensitive drum  320 , which leads to a fuser  311 .  
         [0026]    Exemplary Implementation and Operation  
         [0027]    Implementation and operation will be explained primarily using FIGS. 3 and 4. When printing an image, the photosensitive drum  320  is rotated in the direction indicated by the arrow in the figure (i.e. counterclockwise). First, a charging roller or corona wire  312  uniformly charges the surface of the photosensitive drum  320 . This charge is dissipated from the surface of the drum when exposed to light. Next, a laser beam  310  from a laser-scanning unit  314  selectively irradiates the surface of the photosensitive drum  320  to form an electrostatic latent image in the charges on the surface of the photosensitive drum  320 .  
         [0028]    The laser beam  310  is modulated by a laser driver of the laser-scanning unit  314  in accordance with image data that is provided to the printing device to be printed. The print controller  308  controls the laser-scanning unit  314 , modulating the laser-scanning unit  314  according to the image data. Consequently, as the laser beam  310  is scanned across the surface of the drum  320  and modulated according to the image data, the image is written in latent form into the charges on the surface of the photosensitive drum  320 .  
         [0029]    A developing device is provided with the photosensitive drum  320  and includes a developer cylinder  316  and a toner supply  318 . A developing bias voltage is applied to the developer cylinder  316  from a power supply (not shown). This bias voltage charges the toner that is carried on the developer cylinder  316 . The charge imparted to the toner is of the same polarity as the charge applied on the surface of the photosensitive drum  320  by the charging roller or corona wire  312 . Consequently, the charged toner adheres to the electrostatic latent image formed on the surface of the photosensitive drum  320  from which the like charge has been dissipated and is repelled by other portions of the drum  320  where a like charge remains. In this way, the image is formed on the photosensitive drum  320  with toner.  
         [0030]    With the rotation of the photosensitive drum  320 , charged toner is adhered to the entire latent image on the surface of the photosensitive drum  320  by the developer cylinder  316 . This fully develops the latent image on the photosensitive drum  320 . Further, with the rotation of the photosensitive drum  320 , sheets of print media from a supply of print media (not shown) are sequentially delivered sheet by sheet to impinge upon and stop at a pair of resist rollers (not shown). The paired resist rollers are rotated at a timing so adjusted to make a leading edge of a sheet of print medium register with the image on the photosensitive drum  320 . The print medium is guided by a part of the outer surface of a cartridge and delivered to a transfer nip between the photosensitive drum  320  and a transfer roller  322 .  
         [0031]    As the print medium passes between the photosensitive drum  320  and the transfer roller  322 , the print medium is charged to at least 1000V to efficiently transfer the toner of the developed image to the print medium (e.g., paper) and to hold the toner onto the print medium until it is fused. A toner image on the photosensitive drum  320  is then transferred to the print medium by the transfer roller  322 .  
         [0032]    After receiving the image transferred from the drum  320 , the print medium is conveyed to a transfer nip between the laminate transfer roller  323  and the laminate applicator  332 . As the print medium passes between the laminate transfer roller  323  and the laminate applicator  332 , laminate powder is transferred to the print medium.  
         [0033]    [0033]FIG. 4 demonstrates how the laminate powder  340  is transferred from the laminate applicator  332  to the print medium. As the laminator cylinder  344  rotates, as indicated by the arrow, the outer edge of the laminator cylinder  344  passes through the laminate powder reservoir  342  receiving a substantially consistent layer of laminate powder  340 . As the laminator cylinder  344  continues to rotate, it comes into contact with the print medium where the layer of laminate powder is transferred from the outer edge of the laminator cylinder  344  onto the print medium.  
         [0034]    Once substantially coated with laminate powder  340 , the print medium is transported through a transport path  324  to a fuser  311 . The fuser  311  includes a fixing nip disposed between a fixing roller  313  and a pressing roller  326 . Once at the fuser  311 , heat and pressure are applied to the print medium to substantially fix the toner and the laminate powder  340  on the print medium by partially melting them. Thereafter, the print medium is discharged from the printing device.  
         [0035]    [0035]FIG. 7 demonstrates a printer control executed in the control unit. According to one embodiment, the printer driver associated with the present invention is loaded on a computing device and includes a finishing option for laminating. The printer control  700  initializes the print mode  710 . Once laser printing  720  is selected, the user of the computing device is able to both select the printing process  722  and choose from a number of finishing options  724  including none  726  and lamination  730 . If no finishing option is selected, the print medium receives a laser printed toner image as disclosed above and continues on to the fusing process  728  so that the image may be affixed to the print medium. However, if the lamination  730  or other finishing option  740  is selected, the lamination process  732  is performed after receiving the toner image but prior to sending the print medium to the fusing process  728 .  
         [0036]    The present design eliminates the problem of requiring multiple steps in order to print and laminate a print medium by incorporating both steps in one printing device. Under principles of the present invention, the laminate applicator  332  takes a form similar to that of a toner cartridge. The proposed embodiment of the laminate applicator  332  eliminates the need for additional space to house a laminating machine, reduces the cost of manufacture, and improves time required to complete a print/lamination job.  
         [0037]    Alternative Embodiments  
         [0038]    Alternative embodiments of the claimed invention can be seen in FIGS. 5 and 6. FIG. 5 depicts a perspective view of an alternative embodiment of a printing device in which two laminate applicators  332  are employed according to principles of the present invention. In this embodiment, the laminate powder  340  may coat both sides of the print medium prior to entering the fuser  311 . It will be appreciated by one of ordinary skill in the art that any number of laminate applicators  332  may be used without varying from the teachings of the present invention. Additionally, any number of print medium fusers may be employed to affix the toner and laminating powder to the print medium. These fusers may include, but are not limited to: infrared heaters, a xenon flash lamp, or other heat treatments.  
         [0039]    Alternatively, FIG. 6 demonstrates an embodiment of the present invention that allows selective lamination of the print medium. As illustrated in FIG. 6, an additional laser beam  310  modulated by a laser driver of a laser-scanning unit  314  scans a second photosensitive drum  320 . As the laser beam  310  is scanned across the surface of the drum  320  and modulated according to supplied image data, the laminate image is written in latent form into the charges on the surface of the photosensitive drum  320 . As the photosensitive drum  320  rotates, it comes into contact with a laminate applicator containing laminate powder  340  of the same polarity as the charge applied on the surface of the photosensitive drum  320  by a charging roller or corona wire  312 . Consequently, the charged laminate powder  340  adheres to the electrostatic latent image formed on the surface of the photosensitive drum  320  from which the like charge has been dissipated and is repelled by other portions of the drum  320  where a like charge remains. In this way, the selective laminate image is formed on the photosensitive drum  20  with laminate powder. With the rotation of the photosensitive drum  320 , charged laminate powder is transported from the surface of the photosensitive drum  320  to the print medium. The print medium then continues onward to the transport path  324  and the fuser  311  where the toner and laminate powder are substantially fused to the print medium.  
         [0040]    In conclusion, the present invention, it its various embodiments, enables a user to create laminated output directly from a printing device. By eliminating the need for an additional laminating device the present invention reduces the space needed to perform the desired operation, reduces cost, and, reduces processing time.  
         [0041]    Under principles of the present invention, a cartridge may be provided for the printing/laminating devices described herein. Such a cartridge may include a supply of toner as well as a supply of laminating powder. Alternatively, separate cartridges of toner and laminating powder may be provided within the printer.  
         [0042]    The preceding description has been presented only to illustrate and describe the invention. It is not intended to be exhaustive or to limit the invention to any precise form disclosed. Many modifications and variations are possible in light of the above teaching. It is intended that the scope of the invention be defined by the following claims.