Abstract:
Several embodiments of apparatus and methods are disclosed. One or more of the disclosed example devices includes a flexible member having first and second tensioning members.

Description:
BACKGROUND 
   Tensioned belts are sometimes employed to transfer rotational power from a rotating shaft to another object, such as an item coupled to the belt or to a pulley. Having a high belt tension may be problematic in that the high belt tension may lead to motor heating and rapid wear of motor bushings for the motor driving the rotating shaft. Having a low belt tension may also be problematic in that slipping may occur between the belt and the shaft or pulley. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  schematically illustrates an inkjet printing system in accordance with an example embodiment. 
       FIG. 2  is a side view of a portion of a carriage drive assembly, in accordance with an example embodiment. 
       FIG. 3  is a side view of a portion of a carriage drive assembly in accordance with another example embodiment. 
   

   DETAILED DESCRIPTION 
     FIG. 1  illustrates an example embodiment of a portion of an inkjet printing system  100 . Inkjet printing system  100  includes an inkjet printhead assembly  102 , an ink supply assembly  104 , a carriage assembly  106 , a media transport assembly  108 , and an electronic controller  120 . Inkjet printhead assembly  102  includes a printhead that ejects drops of ink through a plurality of orifices or nozzles  122  toward a print medium  126  so as to print onto print medium  126 . Print medium  126  may comprise any type of suitable media, such as, but not limited to, paper, cardstock, transparencies, and the like. In some embodiments, nozzles  122  are arranged in one or more columns or arrays such that properly sequenced ejection of ink from nozzles  122  causes characters, symbols, and/or other graphics or images to be printed upon print medium  126  as inkjet printhead assembly  102  and print medium  126  are moved relative to each other. 
   Ink supply assembly  104  supplies ink to printhead assembly  102  and includes a reservoir  130  for storing ink. As such, ink flows from reservoir  130  to inkjet printhead assembly  102 . In some embodiments, inkjet printhead assembly  102  and ink supply assembly  104  are housed together in an inkjet print cartridge or pen as defined by dashed line  140 . In other embodiments, ink supply assembly  104  and/or reservoir  130  are separate from ink printhead assembly  102  and supply ink to inkjet printhead assembly  102  from an off-axis position. In some embodiments, the reservoir  130  of ink supply assembly  104  may be removed, replaced, and/or refilled. 
   Carriage assembly  106  positions inkjet printhead assembly  102  relative to media transport assembly  108 , and media transport assembly  108  positions print medium  126  relative to the inkjet printhead assembly  102 . Thus, a print zone  132  is defined adjacent to nozzles  122  in an area between inkjet printhead assembly  102  and print medium  126 . In a scanning-type printing system, carriage assembly  106  moves inkjet printhead assembly  102  relative to media transport assembly  108  to scan print medium  126 . As such, carriage assembly  106  includes a carriage and a carriage drive assembly, as described below. Thus, in some embodiments, the entire print cartridge  140  is positioned in and supported by the carriage and the carriage drive assembly moves print cartridge  140 , including inkjet printhead assembly  102 , back and forth across print medium  126 . In other embodiments, the printhead assembly  102  is positioned in and supported by the carriage while the ink supply assembly  104  and reservoir  130  are not carried by the carriage. 
   Electronic controller  120  communicates with the inkjet printhead assembly  102 , carriage assembly  106 , and media transport assembly  108 . Electronic controller  120  receives data  122  from a host system, such as a computer, and may include a memory for temporarily storing data  122 . Data  122  represents, for example, a document and/or file to be printed. As such, data  122  forms a print job for inkjet printing system  100  and may include one or more print job commands and/or command parameters. 
   Electronic controller  122  provides control of inkjet printhead assembly  102  including timing control for ejection of ink drops from nozzles  122 . Electronic controller  122  also provides control of carriage assembly  106  including timing and a direction of movement relative to print medium  126 . As such, electronic controller  120  defines a pattern of ejected ink drops which form characters, symbols, and/or other graphics or images on print medium  126 . 
     FIG. 2  illustrates a portion of an example carriage assembly  200  that may be used in an imaging device, such as the inkjet printing system  100 . As shown, the carriage assembly  200  includes a carriage  202 , a drive pulley  204 , an idler pulley  206 , and a belt  210  disposed about the pulleys  204 ,  206 . The drive pulley  204  and the idler pulley  206  are shown in this embodiment as being spaced from each other by a fixed distance and generally disposed in the same plane. The drive pulley  204  is coupled to a motor (not shown) by shaft  208  in a manner than permits the motor to transfer rotational power to the drive pulley  204  via the shaft  208 . The motor thus drives the drive pulley  204  in different directions in response to control signals received from a suitable controller, such as the electronic controller  120  ( FIG. 1 ). 
   The belt  210  comprises an elongated flexible member and, in some embodiments, comprises a timing belt. In the embodiment shown in  FIG. 2 , the belt  210  includes teeth  214  formed therein and sized to engage grooves (not shown) formed on the periphery of the pulleys  204 ,  206 . In alternative embodiments, the belt  210  may comprise a flat belt disposed about pulleys without grooves formed therein. The belt  210 , in alternate embodiments, may comprise an endless belt. 
   The belt  210  may be formed any of a variety of suitable materials, including, for example, a nylon fabric. In some embodiments, the belt  210  does not significantly stretch axially under loads common to the assembly  200 . 
     FIG. 2  also illustrates the belt  210  being split and having ends  216 ,  218 . The carriage  202  is elastically or resiliently coupled to the belt  210  via tensioning members  226 ,  228 . The tensioning members  226 ,  228  may comprise springs or other suitable elastic tensioning members. In some embodiments, the tensioning members  226 ,  228  may comprise, for example, leaf springs, coil springs, wave springs, or the like and serve to tension the belt  210 . 
   The carriage  202  serves as a base for carriage assembly  106  and is shown as being adapted to carry and support a printhead assembly  222  therein. The printhead assembly  222  may be configured and may operate in a manner similar to the printhead assembly  102  described above. 
   The tensioning members  226 ,  228  serve to tension the belt  210  and to filter vibrations from the belt  210 , according to some embodiments. Pursuant to some embodiments, vibrations, such as those that may originate at the motor may be transferred to the belt  210  via the shaft  208  and the pulley  204 . The tensioning members  226 ,  228 , in some of these embodiments may serve to at least partially reduce, or dampen, these vibrations such that these vibrations have less effect on the carriage  202  and printhead assembly  222 . 
   In the configuration shown in  FIG. 2 , the tensioning members  226 ,  228  act substantially independently and provide for similar belt tensions regardless of the direction of motion of the belt  210 . Since the tension of the belt  210  is not significantly dependent upon the direction of motion of the belt, low belt tensions can be employed. These low belt tensions may also permit usage of a smaller motor to drive the pulley  204 . 
   The tensioning members  226 ,  228  may be coupled to the carriage  202  by any of a variety of suitable ways. For example, in some embodiments the tensioning members  226 ,  228  may be coupled to the carriage  202  by coupling an end of each of the tensioning members  226 ,  228  to the carriage  202  by a suitable respective fastener (not shown). Clips, adhesives, or other coupling members or materials may alternatively be used to couple the tensioning members  226 ,  228  to the carriage  202 . 
   Similarly, the tensioning members  226 ,  228  may be coupled to the belt  210  by any of a variety of suitable ways. The tensioning members  226 ,  228  may be coupled to the belt  210  at or adjacent the ends  216 ,  218 . In some embodiments, the tensioning members  226 ,  228  are coupled to the ends  216 ,  218  of the belt  210 . Further, as shown in  FIG. 2 , the carriage  202  is substantially centered between the tensioning members  226 ,  228 . 
   In an example inkjet printing implementation, the carriage  202  may have a mass in the range of about 20 grams to 1 kilogram and may nominally have a mass of about 90 grams. Moreover, in this example embodiment, the tensioning members  226 ,  228  may have a spring constant rate of about 0.75 Newton/mm. The spring constant rate may be in the range of about 0.1 to 7.5 Newton/mm in other inkjet printing embodiments. Further, the belt  210  may have a tension of about 2.5 Newtons. In other inkjet printing embodiments, the belt  210  may have a tension in the range of about 1 to 25 Newtons. Linear acceleration of the carriage  202  may be about 1.2 g in this example embodiment. In other inkjet printing embodiments, the linear acceleration of the carriage may be in the range of about 0.5 to 5.0 g. It should be understood that embodiments of the present subject matter may be outside these example ranges. These ranges are provided by way of example and are non-limiting. Further, embodiments of the present subject matter may be used in applications other than inkjet printing. 
     FIG. 3  illustrates a portion of an example carriage assembly  300  that may be used in an imaging device, such as the inkjet printing system  100 . The carriage assembly  300  is configured the same as the carriage assembly  200  described above, except as follows. The carriage  202  is coupled to the belt  210  via leaf springs  326 ,  328 . The leaf springs  326 ,  328  may be formed of sheet metal or other suitable material and serve to tension the belt  210 . 
   Although the present disclosure has been described with reference to example embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope thereof. For example, although different example embodiments may have been described as including one or more features providing one or more benefits, it is contemplated that the described features may be interchanged with one another or alternatively be combined with one another in the described example embodiments or in other alternative embodiments. The present subject matter described with reference to the example embodiments and set forth in the following claims is manifestly intended to be broad. For example, unless specifically otherwise noted, the claims reciting a single particular element also encompass a plurality of such particular elements.