Abstract:
In one embodiment, a material supply device includes: a reservoir defined at least in part by a exterior wall, the wall having an elongated opening therein; an elongated surface close to and extending along the opening in the exterior wall of the reservoir, the surface movable relative to the wall; and a means for moving material directly from the reservoir to the surface through the slot.

Description:
BACKGROUND  
       [0001]     Stirring devices are often used in the toner reservoir in laser printers to keep toner readily available to the developer roller. Stirring contributes to toner wear, which can degrade print quality and limit the life of a print cartridge.  
         [0002]     Laser printers typically are designed to function in a horizontal orientation—the axes of the photoconductor and developer roller are horizontal. Horizontal laser printers can take up more space on a work surface than a vertically oriented laser printer. That is to say, a vertical laser printer may have a smaller “footprint” than a horizontal laser printer. Horizontal laser printers, however, cannot simply be tipped up on end to function as a vertical laser printer because the toner delivery system cannot evenly supply toner to the developer roller as the toner supply is depleted. 
     
    
     DRAWINGS  
       [0003]      FIG. 1  is an elevation view of a vertically oriented material supply device according to one embodiment of the invention.  
         [0004]      FIG. 2  is a section view taken along the line  2 - 2  in  FIG. 1 .  
         [0005]      FIG. 3  is an elevation view of a vertically oriented toner supply device according to one embodiment of the invention.  
         [0006]      FIG. 4  is a section view taken along the line  4 - 4  in  FIG. 3 .  
         [0007]      FIG. 5  is a perspective view of a vertically oriented laser printer in which embodiments of the invention may be implemented.  
         [0008]      FIG. 6  is a plan view diagram illustrating a vertically oriented laser printer, such as the one shown in  FIG. 5 , according to one embodiment of the invention.  
         [0009]      FIGS. 7 and 8  illustrate print cartridges that may be used in a vertically oriented laser printer, according to embodiments of the invention. 
     
    
     DETAILED DESCRIPTION  
       [0010]     Embodiments of the invention were developed in an effort to provide a toner supply for laser printers that does not require stirring and that functions in a vertical orientation even as the toner supply is depleted. Some embodiments, therefore, are described with reference to a toner supply device and a laser printer. Embodiments of the invention, however, are not limited to toner supply or to use in laser printers.  
         [0011]      FIG. 1  is an elevation view of a vertically oriented material supply device  10  that includes a supply tube  12  for containing a material and a roller  14 .  FIG. 2  is a section view taken along the line  2 - 2  in  FIG. 1 . Referring to  FIGS. 1 and 2 , tube  12  and roller  14  are oriented vertically or nearly vertical and positioned parallel to one another. Tube  12  and roller  14  are supported on each end by a frame  16 . Tube  12  is stationary, at least with respect to roller  14 . Roller  14  rotates at the urging of a motor  18  through a gear train  20 . Material is introduced into tube  12  through a hopper  22  connected to a top end  24  of tube  12 . Tube  12  or tube  12  in combination with hopper  22  form a reservoir for material to be transferred to roller  14 . A slot  26 , shown in  FIG. 2 , extends lengthwise along tube  12 . Roller  14  is positioned close to tube  12  so that, as roller  14  rotates and its outer surface  28  moves past slot  26 , material may be transferred from tube  12  through slot  26  onto that portion of roller surface  28  facing slot  26 . In the embodiment shown in  FIG. 1 , slot  26  extends between collars  30  that support tube  12  on frame  16  allowing the transfer of material along a corresponding length of roller  14  between support collars  32 .  
         [0012]     Slot  26  and the gap  34  between tube  12  and roller  14  are configured to allow the desired transfer of material from tube  12  onto roller surface  28  as roller  14  rotates and surface  28  moves past slot  26 . For thinner materials that flow more easily, it is expected that a narrower slot  26  and a smaller gap  34  will be used to allow the desired transfer of material onto a faster moving roller surface  28 . For thicker materials that flow less easily, it is expected that a wider slot  26  and a larger gap  34  will be used to allow the desired transfer of material onto a slower moving roller surface  28 .  
         [0013]     As used in this document: “tube” means a hollow elongated cylinder; “roller” means a rotatable cylinder; “cylinder” means the surface traced by a straight line moving parallel to a fixed straight line and intersecting a fixed planar closed curve; “slot” means a narrow opening or groove; “facing” means oriented toward; “close” means having sufficiently little space between items to allow the transfer of material from one item to the other item through a slot or other opening; and “nearly vertical” means within 5° of vertical. In the embodiment shown in  FIGS. 1 and 2 , tube  12  and roller  14  have a circular cross section. Other cross sections are possible.  
         [0014]      FIG. 3  is an elevation view of a vertically oriented toner supply device  36  such as might be used in a vertically oriented laser printer.  FIG. 4  is a section view taken along the line  4 - 4  in  FIG. 3 . Referring to  FIGS. 3-4 , device  36  includes a toner supply tube  38  containing toner  40  and a developer roller  42 . Tube  38  and roller  42  are oriented vertically and positioned parallel to one another. Tube  38  and roller  42  are supported on each end by a frame  44 . Tube  38  is stationary. Roller  42  rotates at the urging of a motor  46  through a gear train  48 . Toner is introduced into tube  38  through a hopper  50  connected to a top end  52  of tube  38 . A slot  54 , shown in  FIG. 4 , extends lengthwise along tube  38 . Roller  42  is positioned close to tube  38  so that, as roller  42  rotates and its outer surface  56  moves past slot  54 , toner  40  may be transferred from tube  38  through slot  54  onto that portion of roller surface  56  facing slot  54 . Slot  54  extends between collars  58  that support tube  38  on frame  44  allowing the transfer of toner along a corresponding length of roller  42  between support collars  60 .  
         [0015]     The toner particles in conductive toners commonly used in many monochrome laser printers contain some form of iron. A magnet  62  mounted inside developer roller  42  attracts such toner particles at slot  54  to roller surface  56 . Other means for moving the toner from the supply tube to the developer roller may be used. For example, the conductive toner particles commonly used in color laser printers do not contain any magnetic material. Such non-magnetic toner particles may be charged in supply tube  38 . A corresponding charge applied to developer roller  42  can then be used to attract the charged toner particles onto roller surface  56 . Gravity could also be used to move (or help move) toner from the supply tube to the developer roller. In a horizontally oriented toner supply device, for example, gravity might be the only means needed for moving toner from the supply tube to the developer roller.  
         [0016]     As developer roller  42  rotates and roller surface  56  moves past slot  54 , a thin film  64  of toner is formed on roller surface  56 . Slot  54  and the gap  66  between tube  38  and roller  42  are configured to allow the desired transfer of toner  40  onto roller surface  56 . For a typical dry toner in which the toner particles have a nominal diameter of 6-8 microns, a slot  54  1,000-2,500 microns wide and a gap  66  of 20-50 microns between tube  38  and roller surface  56  will allow the formation of a toner film  64  of about 50-100 microns on a typical developer roller  42 . This is just one example of a configuration that may be implemented in a laser printer. Other configurations are possible. For example, the configuration of slot  54  and gap  66  may be adjusted for the use of different size toner particles in dry toners, or possibly even for the use of liquid toners, as well to accommodate different sizes, shapes and/or performance characteristics of developer roller  42 .  
         [0017]      FIGS. 5 and 6  show a vertically oriented laser printer  68 . Printer  68  illustrates one exemplary implementation for a toner supply device such as device  36  described above with reference to  FIGS. 3 and 4 . Referring first to  FIG. 5 , sheets  70  of paper or other print media are fed into printer  68  from an input tray  72  and printed sheets  74  are discharged to an output tray  76 . A replaceable print cartridge  78  and other printer components are enclosed in a housing  80 .  
         [0018]     Referring now also to  FIG. 6 , printer  68  includes a charging roller  82  for charging the surface of a photoconductive drum  84  to a relatively high and substantially uniform level. The surface of photoconductive drum  84  includes photosensitive material that can be charged and discharged. A laser scanner  86  emits a beam of light  88  onto the uniformly charged surface of photoconductive drum  84  to discharge select areas of the surface of drum  84  corresponding to the image to be printed. The light beam is reflected off a multifaceted spinning mirror (not shown) to scan the beam across the surface of photoconductive drum  84 . Photoconductive drum  84  rotates so that each successive scan of light beam  88  falls on drum  84  immediately after the previous scan.  
         [0019]     Printer  68  includes a toner supply device  90  such as device  36  described above with reference to  FIGS. 3 and 4 . A film of toner is formed on the surface of a developer roller  92  as roller  92  rotates past a slotted toner supply tube  94 . The surface of drum  84  exposed to light beam  88  rotates into contact with developer roller  92 . Toner on the surface of developer roller  92  is attracted to and sticks on the discharged areas of the surface of drum  84 . Toner is thereby transferred from developer roller  92  to drum  84  in the pattern of the latent image formed by the discharged areas on the surface of drum  84 . As drum  84  continues to rotate, the toner on drum  84  is transferred to print media  70  at the nip between drum  84  and a transfer roller  96  to form the desired image on media  70 . Transfer roller  96  may be charged to help draw the toner off drum  84  onto media  70 . The surface of drum  84  may be cleaned of excess toner and then completely discharged before a uniform charged is restored by charging roller  82  in preparation for the next toner transfer.  
         [0020]     As shown in  FIG. 6 , replaceable print cartridge  78  includes charging roller  82 , photoconductive drum  84  and toner supply device  90 . While this arrangement for the replaceable print cartridge is typical of many laser printers, other arrangements are possible. For example, in some, usually less expensive, laser printers, the replaceable print cartridge may include only the toner supply device or only the toner supply device and the photoconductive drum.  
         [0021]     Each sheet of print media  70  is advanced to the photoconductive drum  84  by a sheet feed mechanism  98 . Feed mechanism  98  includes a motor driven feed roller  100  and a pair of registration rollers  102 . As feed roller  100  rotates, the surface of feed roller  100  contacts a sheet  70  and pulls it into printer  68  until the leading edge of sheet  70  moves into the nip between registration rollers  102 . Registration rollers  102  advance sheet  70  fully into the imaging area where it is engaged between drum  84  and transfer roller  96  and toner is applied as described above. Sheet  70  now with toner applied is advanced along the media path through printer  68  to a fuser  104 . Fuser  104  includes a fusing roller  106  and a pressure roller  108 . One or both rollers  106  and  108  are heated so that as media sheet  70  passes between rollers  106  and  108  toner is fused to the media through the application of heat and pressure. Each sheet is then discharged to output tray  76  as a printed sheet  74 .  
         [0022]     Referring still to  FIG. 6 , print data from a host computer or other data source received by printer  68  is processed by a formatter  110  and controller  112 . Formatter  110  typically formulates and stores an electronic representation of each page to be printed and breaks the page down into a series of lines one pixel high. The data for each line is sent to controller  112  which drives laser scanner  86  and controls the other operative components of printer  68 . Each line of data is used to modulate light beam  88  emitted by laser scanner  86 . While formatter  110  and controller  112  are depicted as discrete components in  FIG. 6 , each containing its own processor and associated programmable memory, the formatter and controller functions are often integrated into a single electronic component.  
         [0023]      FIGS. 7 and 8  each illustrate one example of a replaceable print cartridge  114  that may be used in a vertically oriented laser printer, such as printer  68  illustrated in  FIGS. 5-6 . Referring to  FIGS. 7 and 8 , print cartridge  114  includes a housing  116  enclosing a charging roller  118 , a photoconductive drum  120  and a toner supply device  122 . Housing  116  is partially cut-away along the wavy line in each figure to better illustrate internal components  118 ,  120  and  122 . A hinged cover  123  protects photoconductive drum  129  when cartridge  114  is not installed in a printer. When cartridge  114 , cover  123  swings up, as indicated by the dashed lines  125 , to expose photoconductive drum  120  for printing operations. Toner supply device  122  includes a slotted supply tube  124  and a developer roller  126 . In the embodiment shown in  FIG. 7 , toner supply device  122  is configured like device  36  described above with reference to  FIGS. 3 and 4 . In the embodiment shown in  FIG. 8 , toner supply device  122  also includes a flexible blade  128  that spans part of an expanded slot  130  in supply tube  124 . Blade  128 , which is often referred to as a doctor blade, meters the amount of toner applied to the surface of developer roller  126  to help ensure a uniform toner film on roller  126 . The extent to which doctor blade  128  spans slot  130  defines the width of the opening through which toner moves from supply tube  124  to roller  126 .  
         [0024]     The present invention has been shown and described with reference to the foregoing exemplary embodiments. It is to be understood, however, that other forms, details and embodiments may be made without departing from the spirit and scope of the invention which is defined in the following claims.