Abstract:
A system to determine the presence and width of a media within a printing system is disclosed which includes a pair of adjustable media guides is provided about a carriage and is axially spaced apart along the length of the carriage. The guides may be manipulated along a horizontal axis in a sliding, synchronized manner and such that the center line of media is maintained along the centerline of the print station. A sensor is provided and affixed to the carriage, the sensor being operable for emitting an optical signal through an aperture located in the carriage. At least one of the guides includes an obstruction which may protrude into the path of the optical signal at defined locations. As the guides move about the horizontal axis, the obstruction may block or otherwise interrupt the optical signal, thereby signaling the sensor and the printer of the media&#39;s presence and width.

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
       [0001]    This application claims priority to provisional patent application 61/488,890, filed May 23, 2011, and entitled “Media Width Sensor”, the contents of which are incorporated in full by reference herein. 
     
    
     FIELD OF INVENTION 
       [0002]    The present invention generally relates to the field of image forming apparatus and devices, and in particular, to sensors operable for determining the width of a media sheet or web as it moves along a media path within a print station of the image forming apparatus or device. 
       BACKGROUND 
       [0003]    Printing systems such as copiers, printers, facsimile devices or other systems having a print engine for creating visual images, graphics, texts, etc. on a page or other printable medium typically include various media feeding systems for introducing original image media or printable media into the system. Examples include thermal transfer printers. Typically, a thermal transfer printer is a printer which prints on media by melting a coating of ribbon so that it stays glued to the media on which the print is applied. It contrasts with direct thermal printing where no ribbon is present in the process. Typically, thermal transfer printers comprise a supply spindle operable for supplying a media web and ribbon, a print station, and a take up spindle. New ribbon and media is fed from the supply spindle to the print station for printing and then the ribbon is wound up by the take up spindle while the media is exited from the print station. The media feed path typically includes media guide structures provided at predetermined locations operable for registering inserted media by moving one or both of the guides to engage opposite sides of the media, thereby fixing the location of the media relative to the path within the print system. 
         [0004]    Conventional approaches for media width registration and identification include manual identification with no sensing means, wherein a user is prompted to input the media size and orientation. Heretofore, conventional approaches yield undesirable results. For instance, conventional approaches fail to provide for automatic adjustments in printhead pressure, ribbon supply and take up tension and rewinder tension due to variances in the media width. Further, conventional approaches fail to provide the printer with an ability to compare the width of the image to be printed with the actual media width. Such failures oftentimes lead to off center image printing, printing defects or printer failure. Indeed, should the media width not be accommodated for, wax (ink) may be undesirably deposited on the platen roller or firing elements on the printhead in free space may occur. One skilled in the art will appreciate that firing elements in free space may cause the elements to overheat and burn out. 
         [0005]    Thus, there remains a need for improved media width sensing techniques and apparatus by which an automatic or semi-automatic determination of media width is provided and by which the need for width sensing system calibration can be managed. It would, therefore, be desirable to provide a sensing apparatus or device operable for detecting and determining the media width along a feed path of a printer. By detecting and determining the media width in the printer, automatic adjustments can be made to the printhead pressure, ribbon supply tension, ribbon supply take up, and rewind tension, thereby ensure a higher quality printed image and prolonger printer operation. Further, by detecting and determining the media width in the printer, associated software can compare the width of the image to be printed to the media width and notify the operator that they may be printing off the media. 
       SUMMARY OF THE INVENTION 
       [0006]    The present invention is designed to overcome the deficiencies and shortcomings of the devices conventionally known and described above. The present invention is designed to reduce the manufacturing costs and the complexity of assembly. In all exemplary embodiments, the present invention is directed to sensing apparatus or sensors and methods of use to determine a width of a media sheet or web moving along a defined media path within a printing system. In an exemplary embodiment, a carriage or base is provided which is mountable within a printing system. A pair of adjustable media guides is provided and connected to the carriage via channels or slots which are located within a portion of the carriage. The media guides are configured to receive and maintain media or a web for printing and preferably axially spaced apart along the length of the carriage. Further, the media guides are configured and adapted such that they can be manipulated or moved along a horizontal axis of the carriage in a sliding manner. In exemplary embodiments, the sliding movement of the guides along the horizontal axis occurs in a synchronized manner. In still other exemplary embodiments, the guides are configured such that the center line of media which is passing along a media feed path is maintained along the centerline of the print station. 
         [0007]    In all exemplary embodiments, a sensor is provided, affixed to the carriage and in signal communication with control circuitry of the printing system. The sensor is configured and operable for emitting at least one optical signal or light beam through at least one aperture located in the carriage. At least one of the media guides are provided with a tab or other obstruction which is configured and operable for protruding into at least a portion of the path of the at least one optical signal or light beam emitted from the sensor at defined locations, the defined locations corresponding to the widths of various media types used within the printing system. As the media guides move about the horizontal axis of the carriage, the tab may block or otherwise interrupt or obstruct the at least one optical signal or light beam, thereby reflecting the at least one optical signal or light beam back to the sensor and thuds signaling the sensor and the printer of the media&#39;s detection and width. By detecting and determining the media width in the printing station, automatic adjustments can be made to the printhead pressure, ribbon supply tension, ribbon supply take up, and rewind tension, thereby ensuring a higher quality printed image and prolonged printer operation. Further, by detecting and determining the media width in the printer station, associated software can compare the width of the image to be printed to the media width and notify the operator that they may be printing off the media. 
         [0008]    Additional features and advantages of the invention will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the invention as described herein, including the detailed description which follows, the claims, as well as the appended drawings. 
         [0009]    It is to be understood that both the foregoing general description and the following detailed description present exemplary embodiments of the invention, and are intended to provide an overview or framework for understanding the nature and character of the invention as it is claimed. The accompanying drawings are included to provide a further understanding of the invention, and are incorporated into and constitute a part of this specification. The drawings illustrate various embodiments of the invention, and together with the detailed description, serve to explain the principles and operations thereof. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    The present subject matter may take form in various components and arrangements of components, and in various steps and arrangements of steps. The appended drawings are only for purposes of illustrating exemplary embodiments and are not to be construed as limiting the subject matter. 
           [0011]      FIG. 1  is a perspective view of the media guides of the present invention in an open position; 
           [0012]      FIG. 2  is a bottom plan view of the embodiment of  FIG. 1 ; 
           [0013]      FIG. 3  is a cross-sectional view of the embodiment of  FIG. 1 ; 
           [0014]      FIG. 4  is a cross-sectional view of the embodiment of  FIG. 1  at the B-B axis showing the media guide in a fully expanded position; 
           [0015]      FIG. 5  is a bottom plan view of the embodiment of  FIG. 1  with the media guides moved inward along the horizontal axis such that a light beam emitted from the sensor is interrupted; and 
           [0016]      FIG. 6  is a cross-sectional view of the embodiment of  FIG. 1 ; and 
           [0017]      FIG. 7  is a cross-sectional view of the embodiment of  FIG. 1  at the B-B axis showing the media guide in a partially closed position. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0018]    The present invention will now be described more fully hereinafter with reference to the accompanying drawings in which exemplary embodiments of the invention are shown. However, this invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. These exemplary embodiments are provided so that this disclosure will be both thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Further, as used in the description herein and throughout the claims that follow, the meaning of “a”, “an”, and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein and throughout the claims that follow, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise. 
         [0019]    Methods, apparatus and systems are presented herein for feeding original image media web and/or printable media into a printing system and for detecting the presence and determining the width of the inserted media at a print station location. In exemplary embodiments and as shown in  FIGS. 1-7 , a printing system media feeding apparatus  10  is provided, including a carriage or base  100  to support a media or web (not shown) being fed into the system  10 , the base  100  having top and bottom surfaces  102  and  104 , respectively. First and second media guides  106  and  108  are provided about the bottom surface  104  of the base  100  extending outward and about a side of the base  100 . The guides  106 ,  108  are movably attached to the base  100  such that they are operable to engage opposite sides of the media being fed between the guides  106 ,  108 . 
         [0020]    In exemplary embodiments, both guides  106  and  108  are slidable along a horizontal axis (A-A) of the base  100  in synchronism via a rack and pinion system  110  and when pushed together, the guides  102 ,  104  centrally register the inserted media and help ascertain the width thereof. More specifically, the guides  106  and  108  are mounted to first and second racks  112 ,  114  and coupled by a pinion gear  116  on the top surface  102  of the base  100  that cooperatively provide for synchronous translation of the guides  106 ,  108  in a rack and pinion arrangement by which the guides  106 ,  108  can be pushed together to centrally register the media. In exemplary embodiments, the rack and pinion system  110  is located about the top surface  102  of the base  100  and is connected to the guides  106 ,  108  via screws  118 ,  120  that extend through the base  100  at predefined channels or slots  122 ,  124 . 
         [0021]    The printing system  10  further includes a media sensing apparatus or sensor  126  configured for emitting signals used to ascertain the presence and width of registered media between the media guides  106  and  108 . It will be understood by those skilled in the art that the signals emitted by the sensor  126  may be either optical or electrical signals. In exemplary embodiments, the sensor  126  is mounted in a fixed position relative to the top surface  102  of the base  100  and the guides  106  and  108 . The sensor  126  is adapted to detect the presence and/or absence of an obstruction and is in signal communication with control circuitry (not shown) of the printing system  10 . In exemplary embodiments, the control circuitry determines the width of the media based on signals received from the sensor  126 . In one example embodiment, the control circuitry includes a microcontroller with associated memory. The control circuitry may oversee movement of the media sheet along the entire media feed path of the printer, or may just determine the width of the media as it moves through the print station and about the sensor  126 . 
         [0022]    In exemplary embodiments, the sensor  126  may be an optical sensor, a photosensor, a mechanical sensor, or another suitable sensor as known in the art. In exemplary embodiments shown herein, the sensor  126  is an optical sensor. The sensor  126  is provided with at least one light emitting device which is operable for emitting at least one light beam along a first light path through at least one aperture  128  of the base  100 . The sensor  126  is also operable for detecting a reflected light beam along a second light path that is generated by an obstruction and includes a transmitter (not shown) and a receiver (not shown). In example embodiments, the transmitter emits a signal that is detectable by receiver. In one exemplary embodiment, the signal is electromagnetic energy. Thus, the transmitter emits optical energy with a frequency spectrum that is detectable by the receiver. It will be appreciated by those skilled in the art that the transmitter may be embodied as an light emitting diode (LED), laser, bulb or other source. In exemplary embodiments, the receiver changes operating characteristics based on the presence and quantity of optical energy received. It will be appreciated by those skilled in the art that the receiver may be a phototransistor, photodarlington, or other detector. The optical energy may consist of visible light or near-visible energy (e.g., infrared or ultraviolet). 
         [0023]    In exemplary embodiments, the sensor  126  may include an optical emitter or laser module communicably linked to a microcontroller or the control circuitry of the printer. The sensor  126  may be configured to emit an optical signal or beam along a first optical path and receive a reflected optical signal reflected from an obstruction along a second optical path. The sensor  126  may also include a transceiver (not shown). In exemplary embodiments, the transceiver may include an integrated avalanche photodiode (APD) receiver, as APD receivers are particularly well suited for detecting small amounts of light. The transceiver may be configured to receive reflected optical signals and convert them, into electrical signals which may then be transmitted to the control circuitry for a determination of the media&#39;s width and subsequent adjustments to the printing operation. 
         [0024]    In other exemplary embodiments, the sensor  126  is a photo-sensor constituted by a light emitting element that emits light using a light emitting diode (LED) and a light receiving element that receives reflection light reflected from an obstruction and which outputs a voltage on the basis of intensity of the received light. In exemplary embodiments, the sensor  126  is a reflection-type photo interrupter that receives light, which has been emitted from the light emitting element, reflected from an obstruction using the light receiving element and changes its output voltage level in correspondence with the intensity of the received. The output voltage level of the sensor  126  for a case where light reflected from the obstruction at one location is received is higher than that for a case where light reflected from the obstruction at a different location is received. Accordingly, when an approximate center output voltage level is set as a reference voltage, the width of the media may be determined based upon the output voltage level. 
         [0025]    The presence or absence of an obstruction, as determined by the sensor  126 , influences functions of the printing system  10  according to programming within the control circuitry. By detecting and determining the media width in the printing station, automatic adjustments can be made to the printhead pressure, ribbon supply tension, ribbon supply take up, and rewind tension, thereby ensuring a higher quality printed image and prolonged printer operation. Further, by detecting and determining the media width in the printer station, associated software can compare the width of the image to be printed to the media width and notify the operator that they may be printing off the media. The sensor  126  may be used with roll media, although use of the sensor in conjunction with media of other types is also contemplated. Also, in exemplary embodiments, the media width resolution of the sensor  126  is determined by: 
         [0000]      Res=(Max. media width−Min. media width)/(2* N− 1),
 
         [0000]    where N is the number light beams emitted by the sensor. 
         [0026]    In all exemplary embodiments, at least one of the media guides  106 ,  108  include an optical obstruction structure (a tab)  130  that is operatively coupled to the movable media guide so as to move relative to the at least one light beam emitted by the sensor  126  when the guide is moved relative to the base  100  with the tab  130  moving within a sensing gap (over the emitted light beam coming through the aperture) to block or otherwise interrupt the signal path. 
         [0027]      FIGS. 1-4  illustrate the media guides  106 ,  108  in a fully opened position such that none of the light beams emitted by the sensor  126  are blocked or otherwise obstructed. Referring now to  FIG. 5 , the media guides  106 ,  108  are moved inward along the horizontal A-A axis of the base  100  to a predefined location such that tab  130  blocks at least one of the light beams emitted from sensor  126 . Upon further closure of the media guides  106 ,  108  to another predefined location additional light beams will be blocked, thereby providing the control circuitry with additional information to be used in the determination of the media width. Alternatively, in a photo sensor embodiment, as the reflected light is returned the photo sensor can determine the width of the media and signal the control circuitry of the printer. 
         [0028]    Further exemplary embodiments provide a method for detecting and determining a media width in a printing system. The method comprises providing a base or carriage  100  with first and second media guides  106 ,  108 , mounting a sensor  126  in a fixed position relative to the print station. The base  100  within the print station being provided with at least one aperture for permitting emitted optical signals or light beams from the sensor to pass through. At least one media guide is provided with an optical obstruction structure such as a tab or fin which is located in a fixed position relative to the media guide to move relative to the emitted light beam when the media guide is moved relative to the print station. The media guide is then moved to register the media and reflected optical signals are read from the sensor, with the media width being determined based at least partially on the reflected optical signals. In certain implementations, the width determination may include determining two or more possible media widths based on the electrical output signals from the sensor, rendering a selection of the plurality of possible media widths to a user, and determining the media width based on a user selection from a user interface of the printing system. 
         [0029]    The above described examples, moreover, may be employed in calibrated or non-calibrated systems for determining media widths and for registering media being fed into a printing system. Furthermore, while the illustrated examples are described in connection with media feeding systems employing two oppositely adjustable synchronously translating rack and pinion type guide assemblies, other embodiments are possible in which one guide is stationary while the other is translatable. 
         [0030]    The embodiments described above provide advantages over conventional devices and associated methods of manufacture. It will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the spirit and scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents. Furthermore, the foregoing description of the preferred embodiment of the invention and best mode for practicing the invention are provided for the purpose of illustration only and not for the purpose of limitation—the invention being defined by the claims.