Abstract:
This invention relates to a media jam and media bent corner detector, comprising: a carriage; a transducer operatively connected to or adjacent to the carriage; and a piezoelectric film beam operatively connected to the transducer such that a portion of the beam substantially extends into a media path to detect the presence of a media jam or a media bent corner.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention relates to a media jam and media bent corner detector, comprising: a carriage; a transducer operatively connected to or adjacent to the carriage; and a piezoelectric film beam operatively connected to the transducer such that a portion of the beam substantially extends into a media path to detect the presence of a media jam or a media bent corner. 
   2. Description of the Related Art 
   In a high reliability, high speed printing mechanism, it is critical to know if media is jamming up against or under the print heads or if a bent over corner is likely to contact the underside of the print heads. In a paper jam condition, multiple sheets will pile up quickly, making it hard to clear the jam. Also, if the mechanism continues to try to move for media along, it will often shift the print head positions, thereby causing subsequent color printing alignment problems. Bent over corners may cause a problem because they may extend above the paper support surface enough to make contact with the print head nozzles. This could lead to the transfer of objectionable amounts of ink/toner from a print head onto the media which may then carry and transfer the ink/toner onto the next print head. This may then cause a mixing of ink types that could lead to a chemical reaction that clogs the print head. With this in mind, it is known that space and tolerance constraints make it difficult to provide a reliable but inexpensive sensor that can detect a bent piece of media or the beginning of a media jam. Consequently, a more advantageous sensor, then, would be provided if it was reliable and inexpensive and could detect a bent piece of media and/or the beginning of the media jam. 
   It is apparent from the above that there exists a need in the art for a sensor that is reliable and inexpensive, but which at the same time can detect a bent piece of media and/or the beginning of the media jam. It is a purpose of this invention to fulfill this and other needs in the art in a manner more apparent to the skilled artisan once given the following disclosure. 
   SUMMARY OF THE INVENTION 
   Generally speaking, an embodiment of this invention fulfills these needs by providing a media jam and media bent corner detector, comprising: a carriage; a transducer operatively connected to or adjacent to the carriage; and a piezoelectric film beam operatively connected to the transducer such that a portion of the beam substantially extends into a media path to detect the presence of a media jam or a media bent corner. 
   In certain preferred embodiments, the transducer is further comprised of a printed circuit assembly. Also, the piezoelectric film beam is further comprised of a polyvinylidene fluoride (PVDF) piezoelectric film beam. Finally, the detector further comprises isolation grommets and a heavy bracket to prevent high frequency vibrations and shock from being transferred from the carriage to the detector. 
   In another further preferred embodiment, a reliable and inexpensive detector is presented which can detect a bent piece of media and/or the beginning of the media jam. 
   The preferred media jam and media bent corner detector, according to various embodiments of the present invention, offers the following advantages: ease-of-use; excellent media jam detecting characteristics; excellent media bent corner detection characteristics; lightness in weight; improved reliability; and reduced cost. In fact, in many of the preferred embodiments, these factors of media jam detecting characteristics, media bent corner detection characteristics, reliability, and cost are optimized to an extent that is considerably higher than heretofore achieved in prior, known media jam and media bent corner detectors. 
   The above and other features of the present invention, which will become more apparent as the description proceeds, are best understood by considering the following detailed description in conjunction with the accompanying drawings, wherein like characters represent like parts throughout the several views and in which: 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  illustrates a media jam and media bent corner detector assembly, according to one embodiment of the present invention; 
       FIG. 2  illustrates the media jam and media bent corner detector assembly with the grommets and bracket attached, according to another embodiment of the present invention; 
       FIG. 3  shows how a piece of media that is jammed interacts with the media jam and media bent corner detector assembly, according to another embodiment of the present invention; 
       FIG. 4  is a flowchart of a method for interrupting a print job when a media jam or media bent corner has been detected, according to another embodiment of the present invention; 
       FIG. 5  is a flowchart of another method for interrupting a print job when a media jam or media bent corner has been detected, according to another embodiment of the present invention 
       FIG. 6  is a flowchart of a method for moving the carriage to a service/capping mode when a media jam or media bent corner has been detected, according to another embodiment of the present invention; and 
       FIG. 7  is a flowchart of a method for determining if a media jam or media bent corner has been detected, according to another embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   With reference first to  FIG. 1 , there is illustrated one preferred embodiment for use of the concepts of this invention.  FIG. 1  illustrates media jam or media bent corner detector assembly  2 . Assembly  2  includes, in part, carriage  4 , transducer  6 , and piezoelectric film beam  8 . Transducer  6 , preferably, is constructed of a printed circuit assembly (PCA) that is rigidly attached to carriage  4 . Piezoelectric film beam  8 , preferably, is constructed of a polyvinylidene fluoride (PVDF) piezoelectric film beam that is rigidly attached along one end to transducer  6  such that a portion of piezoelectric film beam  8  extends below transducer  6  and into a media path. It is to be understood that piezoelectric film beam  8  should extend at least across the entire width of the media to be measured. It is also to be understood that transducer  6  and piezoelectric film beam  8  can be located away from the carriage  4 . 
   With respect to  FIG. 2 , bracket  20  is placed over piezoelectric film beam  8  and secured by isolation grommets  22  to prevent high frequency vibrations and shock from being transferred from carriage  4  to assembly  2 . Bracket  20 , preferably, is constructed of any suitable, durable, high strength material that is capable of retaining transducer  6  and piezoelectric film beam  8  in place. Isolation grommets  22  are used to secure bracket  20  onto carriage  4 . As can be seen in  FIG. 2 , a portion of piezoelectric film beam  8  extends below carriage  4  and bracket  20 . 
   With respect to  FIG. 3 , under normal circumstances media  32  passes below piezoelectric film beam  8 . However, if a sheet of media  32  becomes jammed, typically a portion  34  of the media  32  extends above drum  30 . When portion  34  extends above drum  30 , portion  34  contacts piezoelectric film beam  8 . This contact with piezoelectric film beam  8  causes piezoelectric film beam  8  to bend or deform. This bending strains transducer  6  and generates an electric charge that is amplified and thresholded to generate a firmware interrupt within a driving circuit (not shown) for driving drum  30 . The firmware interrupt is used to determine the presence of a media jam or media bent corner. It is to be understood that while a media jam has been shown in  FIG. 3 , a media bent corner would also extend above the drum  30 , contact piezoelectric film beam  8  and cause piezoelectric film beam  8  to deform. 
   Various usages of assembly  2  will now be described. With respect to  FIG. 4 , a method  40  for interrupting a print job when a media jam or media bent corner has been detected is shown. Method  40  includes, but is not limited to, the steps of actuating assembly  2  ( FIG. 1 ) when a media jam or a media bent corner contacts piezoelectric film beam  8  ( FIG. 3 ) (step  42 ). Stopping the rotation of drum  30  ( FIG. 2 ) by the firmware interrupt (step  44 ). Finally, the media jam or the media having a bent corner is removed (step  46 ). It is to be understood that a variety of conventional techniques can be employed to assist the user in removing the media jam or the bent corner media. For example, lights can be illuminated to show where the jam/bent corner media is located. Also, graphics on the user interface can show where the jam/bent corner media is located. It is to be understood that the actuating steps  42 - 72  in methods  40 - 70 , respectively, can be further utilized to determine if the jam/bent corner media has been cleared. 
   With respect to  FIG. 5 , another method  50  for interrupting a print job when a media jam or media bent corner has been detected is shown. Method  50  includes, but is not limited to, the steps of actuating assembly  2  ( FIG. 1 ) when a media jam or a media bent corner contacts piezoelectric film beam  8  ( FIG. 3 ) (step  52 ). Stopping the rotation of drum  30  ( FIG. 2 ) by the firmware interrupt (step  54 ). Reversing the rotation of drum  30  to allow for the removal of the media jam or the media having a bent corner (step  56 ). It is to be understood that the flow of the media path can be conventionally reversed to allow for the removal of the media jam or the media having a bent corner. Finally, the media jam or the media having a bent corner is removed (step  58 ). 
   With respect to  FIG. 6 , a method  60  for moving the carriage to a service/capping mode when a media jam or media bent corner has been detected is shown. Method  60  includes, but is not limited to, the steps of actuating assembly  2  ( FIG. 1 ) when a media jam or a media bent corner contacts piezoelectric film beam  8  ( FIG. 3 ) (step  62 ). Stopping the rotation of drum  30  ( FIG. 2 ) by the firmware interrupt (step  64 ). Moving the carriage  4  to a servicing/capping mode such that the print head  10  ( FIG. 3 ) can be conventionally serviced and/or capped (step  66 ). The print head is then conventionally serviced and/or capped. Finally, the media jam or the media having a bent corner is removed (step  68 ). 
   With respect to  FIG. 7 , a method  70  for determining if a media jam or media bent corner has been detected is shown. Method  70  includes, but is not limited to, the steps of actuating assembly  2  ( FIG. 1 ) when a media jam or a media bent corner contacts piezoelectric film beam  8  ( FIG. 3 ) (step  72 ). Stopping the rotation of drum  30  ( FIG. 2 ) by the firmware interrupt (step  74 ). Determining if media is present in the device (step  76 ). If media is present in the device then the media jam or media having the bent corner is removed (step  78 ). However, if media is not present in the device, the assembly  2  is checked for defects (step  79 ). One of the purposes of method  70  is to detect if carriage  4  is creating high frequency vibrations or shock and transferring these to assembly  2 . Even though media may not be present in assembly  2 , a false reading may still result from the vibrations or shock as carriage  4  shuttles back and forth. In this instance, carriage  4  may need to be serviced or replaced. 
   It is to be understood that the flowchart of  FIGS. 4-7  show the architecture, functionality, and operation of one implementation of the present invention. If embodied in software, each block may represent a module, segment, or portion of code that comprises one or more executable instructions to implement the specified logical function(s). If embodied in hardware, each block may represent a circuit or a number of interconnected circuits to implement the specified logical function(s). 
   Also, the present invention can be embodied in any computer-readable medium for use by or in connection with an instruction-execution system, apparatus or device such as a computer/processor based system, processor-containing system or other system that can fetch the instructions from the instruction-execution system, apparatus or device, and execute the instructions contained therein. In the context of this disclosure, a “computer-readable medium” can be any means that can store, communicate, propagate or transport a program for use by or in connection with the instruction-execution system, apparatus or device. The computer-readable medium can comprise any one of many physical media such as, for example, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor media. More specific examples of a suitable computer-readable medium would include, but are not limited to, a portable magnetic computer diskette such as floppy diskettes or hard drives, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory, or a portable compact disc. It is to be understood that the computer-readable medium could even be paper or another suitable medium upon which the program is printed, as the program can be electronically captured, via, for instance, optical scanning of the paper or other medium, then compiled, interpreted or otherwise processed in a single manner, if necessary, and then stored in a computer memory. 
   Those skilled in the art will understand that various embodiment of the present invention can be implemented in hardware, software, firmware or combinations thereof. Separate embodiments of the present invention can be implemented using a combination of hardware and software or firmware that is stored in memory and executed by a suitable instruction-execution system. If implemented solely in hardware, as in an alternative embodiment, the present invention can be separately implemented with any or a combination of technologies which are well known in the art (for example, discrete-logic circuits, application-specific integrated circuits (ASICs), programmable-gate arrays (PGAs), field-programmable gate arrays (FPGAs), and/or other later developed technologies. In preferred embodiments, the present invention can be implemented in a combination of software and data executed and stored under the control of a computing device. 
   It will be well understood by one having ordinary skill in the art, after having become familiar with the teachings of the present invention, that software applications may be written in a number of programming languages now known or later developed. 
   Although the flowcharts of  FIGS. 4-7  show a specific order of execution, the order of execution may differ from that which is depicted. For example, the order of execution of two or more blocks may be scrambled relative to the order shown. Also, two or more blocks shown in succession in  FIGS. 4-7  may be executed concurrently or with partial concurrence. All such variations are within the scope of the present invention. 
   Once given the above disclosure, many other features, modifications or improvements will become apparent to the skilled artisan. Such features, modifications or improvements are, therefore, considered to be a part of this invention, the scope of which is to be determined by the following claims.