Abstract:
Systems and methods for adapting cassette guide movement for size detection includes, in exemplary embodiments, a one-piece member that transmits and rotates a movement of a guide member placed on a side of a sheet to a sheet size detector that detects a position of the guide member, wherein a first end of the connector is connected to the guide member and the second end of the connector is connector is connected to the sheet size detector.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of Invention  
         [0002]     The invention relates to systems and methods for adapting cassette guide movement for size detection.  
         [0003]     2. Description of Related Art  
         [0004]     Adjustable sheet cassettes supply sheets that are stacked in an reproduction system, for example, copiers, printers, facsimile machines, etc. Typically in these systems, individual sheets of copy paper are separately fed through the reproduction system and are processed one at a time. It is thus convenient to have a supply of sheets from which individual sheets are fed.  
         [0005]     A reproduction system must be able to accurately reproduce original documents of various sizes or configurations on various types of copy stock. To facilitate this operational flexibility, it has been customary to provide a supply of cut sheets in a cassette-type or cassette form. These sheet cassettes may be designed for a single fixed size of paper in which case they are only used for storing sheets of that size in the reproduction system. Alternatively, adjustable cassettes may be designed to enable customer adjustment of the cassette for a variety of different sheet sizes.  
         [0006]     With the fixed size cassette, if a printing operation is to be performed to obtain prints on a copy sheet size of a size other than that which is in the fixed cassette, the cassette must be removed from the machine and replaced with another cassette of a different fixed size to enable the operation to be completed. Similarly, with an adjustable cassette, if the size of the paper in the cassette is unsuitable for a particular printing operation, the copy sheets should be removed and replaced with the appropriate size copy sheets for that particular printing operation.  
       SUMMARY OF THE INVENTION  
       [0007]     It is desirable that the reproduction system know the size of the sheets in the cassette as soon as it is inserted in the reproduction system. This enables the machine to automatically provide feedback so that an operator can determine if a particular job can be run with the sheet size in the cassette or if the sheet supply must be replaced. With a copier, for example, it enables the operator to determine if the machine is capable of providing size for size reproduction or automatic reduction and/or automatic enlargement of an original that may be placed on the copying platen.  
         [0008]     Sheet size sensing is usually technically not very difficult. However, it is difficult to develop an economical way to reliable sense multiple sheet sizes. Often, with the larger, expensive reproduction systems, the size of each sheet is determined as the sheet is fed through the reproduction system. However, this approach is rather expensive. Smaller, less expensive reproduction systems typically do not need to sense multiple sizes. These reproduction system do not allow the user to use multiple sizes or only allow for only two different sizes. Flexibility is thus compromised.  
         [0009]     In yet other reproduction systems, cassette guide positions are used to detect the sheet size in the cassette. Typically, a number (n) of discrete digital on-off sensors or switches detect 2 n  different guide positions. These reproduction systems use elaborate electromechanical systems to adapt the guide position for size sensing detection. These systems are complicated mechanisms consisting of sliders, gears, levers, cams, disks, or even pulleys, belts and cables. These systems are also limited in capability, are expensive and are not user friendly.  
         [0010]     There is thus a constant need to simplify sheet size sensing, improve the reliability of sheet size sensing while reducing the manufacturing costs involved in developing a sheet size sensing mechanism, and to make the sheet size sensing more user friendly.  
         [0011]     Because of this, there is a need for systems and methods that can reduce the cost of the sheet size sensing mechanism by reducing the number of mechanical components.  
         [0012]     There also is a need for systems and methods that improves the reliability of the sheet size sensing mechanism by reducing the mechanical play created between a sheet guide and sensor or switch that detects a position of the sheet guide.  
         [0013]     There is also a need for systems and methods that improve the flexibility of a sheet size sensing mechanism by making the mechanism less dependent on actual cassette geometry.  
         [0014]     The systems and methods of this invention adapt the sheet guide position of a removable cassette for conventional sheet size detection with a number of digital on-off sensors or switches.  
         [0015]     The systems and methods of this invention separately allow for cost effective sheet size determination in a reproduction system.  
         [0016]     The systems and methods of this invention separately define the mechanical interface between the cassette guide position and size detecting sensors or switches in the reproduction system.  
         [0017]     The systems and methods of this invention separately use a single mechanical part to transmit the motion from a side guide to a slide plate.  
         [0018]     The systems and methods of this invention separately improve reliability by using a single part to transmit motion from a guide member to a slide plate.  
         [0019]     The systems and methods of this invention separately improve accuracy by eliminating substantially all detrimental part tolerances that are the result of using multiple components.  
         [0020]     The systems and methods of this invention separately improve accuracy by eliminating substantially all of the relative motion between the guide member and the slide plate.  
         [0021]     The systems and methods of this invention separately translate and rotate a guide motion of a guide member.  
         [0022]     The systems and methods of this invention separately translate and rotate a guide motion of a guide member using a rod supported in a channel of a cassette.  
         [0023]     The systems and methods of this invention separately translate and rotate a guide motion of a guide member using a rod that connects the cassette guides with a slider that can easily interact with the sensor or switch array.  
         [0024]     Exemplary systems of this invention may include a sheet cassette including a guide member that is placed on a side of a sheet and is movable between a first position and a second position, a sheet size detector that detects a position of the guide member and is movable between a third position and a fourth position and a one-piece connector with two ends, wherein a first end of the connector is connected to the guide member and a second end of the connector is connected to the sheet size detector.  
         [0025]     These and other features and advantages of this invention are described in, or are apparent from, the following detailed description of various exemplary embodiments of the systems and methods according to this invention.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0026]     Various exemplary embodiments of this invention will be described with reference to the following figures, wherein:  
         [0027]      FIG. 1  is a schematic representation of an automatic printing machine having a sheet cassette according to an exemplary embodiment of this invention;  
         [0028]      FIG. 2  shows a three dimensional view showing in detail the sheet cassette according to the exemplary embodiment of this invention;  
         [0029]      FIG. 3  shows a three dimensional view showing in detail the sheet cassette with the snap fit and flexible pushrod according to the exemplary embodiment of this invention;  
         [0030]      FIG. 4  shows in detail the snap fit and flexible pushrod according to the exemplary embodiment of this invention; and  
         [0031]      FIG. 5  shows a three dimensional view showing in detail the sheet cassette with the slide plate according to the exemplary embodiment of this invention. 
     
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS  
       [0032]     For a general understanding of an electro photographic printer, solid ink printer or copying machine (i.e., reproduction system) in which the features of this invention may be incorporated, reference is made to  FIG. 1 , which depicts schematically various key components thereof. Although this invention for accurately adapting a cassette for size detection is particularly well adapted for use in such a machine, it should be apparent that this embodiment is merely illustrative. Rather, aspects of this invention may be achieved in any cassette in which a broad number of substrate or media types need to be registered and identified in a precise, accurate manner.  
         [0033]     Referring initially to  FIG. 1 , there is shown an automatic xerographic printing machine  100  including the adjustable sheet cassette  110 , according to the present invention. Although the present invention is particularly well suited for use in automatic xerographic apparatus, it is equally well adapted for use with any number of other devices in which cut sheets of material are fed from a sheet supply source. The printer includes a photosensitive drum  120  which is rotated in the direction indicated by the arrow to pass sequentially through a series of xerographic processing stations; a charging station A, an imaging station B, a developer station C, a transfer station D and a cleaning station E.  
         [0034]     A document to be reproduced is placed on imaging platen  160  and scanned by moving optical system  140  including a lamp  142 , mirrors  144 ,  146  and  150  and lens  148  to produce a flowing light image on the drum surface which had been charged at charging station A. The image is then developed at development station C to form a visible toner image. The adjustable sheet cassette  110  according to the present invention is inserted from the front of the machine into the plane of  FIG. 1  in the direction illustrated by arrow  102  in  FIG. 2 . The stack of sheets is supported in the cassette  110  by sheet stack support platform  112  which is urged upwardly by a lift motor or lift springs  114  toward the feed roll  130 . The feeding of sheets is actuated by the controller  170  to feed a sheet from the cassette  110  to registration rolls in synchronous relationship with the image on the drum surface to the transfer station D. Following transfer of the toner image to the copy sheet, the copy sheet is stripped from the drum surface and directed to the fusing station F to fuse the toner image on the copy sheet after which the drum surface itself continues to the cleaning station E where residual toner remaining on the drum surface is removed prior to the drum surface again being charged at charging station A. Upon leaving the fuser, the copy sheet with the fixed toner image thereon is transported to sheet collecting cassette  180 .  
         [0035]     Referring more particularly to  FIGS. 2-5 , the automatic sheet size sensing mechanism will by discussed in greater detail. The cassette  110  illustrated in  FIGS. 2, 3  and  5  have had the sheet support platform  112  and the lift motor  114  removed to facilitate a better understanding of the automatic sheet size sensing mechanism used in the cassettes. Typically, the cassette or drawer bottom is of a one-piece molded plastic, which has additional plastic features incorporated therein or added thereto including, for example, a rear frame member and side frame members  116  and  118 .  
         [0036]     When a stack of sheets is placed on the sheet support platform  112 , a rear sheet edge guide  200  is moved into position in order to contact the rear edge of the sheets. The rear sheet edge guide  200  rides in a mounting slot  202  and two series of slots  204 ,  206  and has at its inboard end a pressure locking member  208  to hold it in place against the rear edge of the stack of sheets. Center registration of all documents can be conventionally provided by a well-known dual rack and pinion connection  210  of opposing side guides  212 ,  214  of the cassette  110 . The side guides  212 ,  214  thus automatically move together towards or away from one another by the same amount, so as to center the sheet stack irrespective of the size of the loaded sheets. As with the rear sheet edge guide  200 , the opposing side guides  212 ,  214  can also include a locking member that holds the opposing side guides  212 ,  214  in place. As should be appreciated, only center registered guides  212  and  214  are shown. However, non-center registered guides can be used.  
         [0037]     In order to adapt the printing mechanism  100  to multiple sheet sizes, the size of the sheets must be detected. The size of the sheets must be detected in order to avoid printing outside of the intended printing area or to utilize all of the printing area. As should be appreciated with solid ink printers, ink that is not transferred to the sheet remains in the printing mechanism  100  where damage to the printing mechanism  100  or future prints may occur. As such, a sheet size detection apparatus determines the size of the sheet and an actuator accurately positions the sheet size detection apparatus.  
         [0038]     The sheet size detection apparatus utilizes the position of the opposing side guides  212 ,  214  in order to activate size detecting sensors or switches in the printing mechanism  100 . It is sufficient to use only one of the opposing side guides  212 ,  214  for size detection because the side guides  212 ,  214  are connected together by the rack and pinion connection  210  and therefore move symmetrically. However, as should be appreciated, the position of the rear sheet edge guide  200  can be used. As shown in  FIG. 2 , the sheet size detection apparatus includes a slide plate  202 , holes  204 , arms  206  and cams  208 . The slide plate  202  moves in the direction indicated by the arrows  102 ,  104  by a mounting slot integral with or attached to the side frame member  116 .  
         [0039]     Attached to or integral with an outside surface of the side frame member  116  are the cams  208 . Attached to or integral with an outside surface of the cams  208  are the arms  206  with one arm  206  attached to each cam  208 . The cams  208  and the arms  206  remain fixed relative to the side frame member  116  in the direction indicated by the arrows  102 ,  104 . However, the cams  208  moves the arms  206  in the direction indicated by the arrow  106  through the various holes  204  of the slide plate  202  and maintains the arms  206  in an extended position when the arms  206  are placed adjacent to the holes  204 . As such, as shown in  FIG. 5 , a mechanical pattern can be created by the arms  206  extending through the holes  204  as indicated by the solid line  210 , for example, to indicate a position of the side guides  212 ,  214 . Conversely, the arms  206  moves the cams  208  in the direction indicated by the arrow  108  outside of the various holes  204  of the slide plate  202  and maintains the cams  208  in a retracted position when the arms  206  are not placed adjacent to the holes  204 .  
         [0040]     In various other exemplary embodiments, the arms  206  used to extend through the holes  204  should be curved in order to permit the arms  206  to sequentially be transported in and out of the holes during the cassette  110  insertion and withdrawal procedure. By so rounding the ends of the individual arms  206 , damage to the individual arms  206  on insertion and withdrawal is avoided.  
         [0041]     As shown in  FIG. 5 , the holes  204  are formed in the slide plate  202  so that the arms  206  and cams  209  can selectively interact with flags that activate sensors or switches of a circuit board (not shown) that is permanently fixed to the main body of the printing apparatus  100 . Although a cam/actuator spring assembly is described, it should be appreciated that an optical array, hall effect sensor array or any other sensor system can be used to transmit data regarding the position of the guide member  212 . Once the slide plate  202  is in the proper position and the appropriate arms  206  contact the appropriate flags, the flags then activate the sensors or switches of the circuit board.  
         [0042]     By activating a given number and sequence of sensors or switches, the controller  170  can then determine the correct sheet size out of a plurality of sheet sizes. As such, the controller  170  can interpret the size of the sheet loaded in the cassette  110  based on the sequence of sensors or switches rather than using continuous size sensing. Interpreting the size of the sheet loaded in the cassette  100  based on the sequence of the sensors and switches is known and discussed, for example, in U.S. Pat. No. 5,596,399 to Dempsey et al. and U.S. Pat. No. 5,333,852 to Milillo et al., which are incorporated herein by reference in their entirety.  
         [0043]     However, in order to align the arms accurately into the appropriate holes conventionally, the position of the side guides are used. When the sheets are placed in the cassette, the side guides are adjusted to fit the sheet width. In adjusting the side guides, a plurality of sliders, gears, cams, levers, belts and cables where used to move the slide plate in order to correspond to a movement of opposing side guide members. The plurality of components thus increase manufacturing costs because a large number of parts have to be created. Also, a lot of play is created because the numerous components are used. Positioning accuracy of the holes relative to the arms is thus compromised.  
         [0044]     To overcome this problem, the invention thus provides the actuator as shown in  FIGS. 2-4  that focuses on the mechanical interface between the position of the side guides  212 ,  214  and the slide plate  202 . In particular, the actuator adapts the position of the side guide  212  for conventional sheet size detection with a number of arms  206  that interact with the flags that activate the sensors or switches of the circuit board. The actuator can thus be applied to any cassette or device in order to detect multiple sheets.  
         [0045]     The actuator, according to an exemplary embodiment of this invention includes a snap fit  302 , a rod  304  and a channel  306 . By using the actuator, the guide member  212  directly moves the slide plate  202  using one piece (i.e., a rod  304 ) that is connected to both the guide member  212  and slide plate  202 .  
         [0046]     As shown in  FIGS. 3 and 4 , the snap fit  302  includes a combination of a hook  312  and a positioning member  314 . The hook  312  and the positioning member  314  together connect the snap fit  302  to the guide member  212  and prevents the actuator from moving independently relative to the guide member  212 . As should be appreciated, any single device or combination currently available or later developed can be used to connect the actuator to the guide member  212  and prevent movement of the actuator independently relative from the guide member  212 . For example, a screw and a screw hole can be used in place of the snap fit  302 .  
         [0047]     The rod  304  is integral with or connected to the snap fit  302  at one end thereof. The rod  304  is also integral with or connected to the slide plate  202  at another end thereof. The rod  304  is directly connected to both the guide member  212  and the slide plate  202  such that when the guide member  212  is moved in the direction indicated by arrow  106  by a given amount, the slide plate  202  also moves in the direction indicated by arrow  104  by the same amount. Conversely, when the guide member  212  is moved in the direction indicated by arrow  108  by a given amount, the slide plate  202  also moves in the direction indicated by arrow  102  by the same amount.  
         [0048]     Positioning accuracy of the slide plate  202  relative to the guide member  212  is thus improved because of the direct transfer of movement. Costs related to sheet size determination is also reduced by using only the snap fit  302  and rod  304 . By using the rod  304  and guide member  306 , more focus is given to the mechanical interface between the guide member  212  and the side plate  202 . As should be appreciated, although the motion of only the side guide  212  is discussed, the motion of the other side guide  214  can be used.  
         [0049]     Located at the bottom of the cassette  110  is a guide channel  306  that guides the rod  304  located therein. In other exemplary embodiments, the guide channel also includes overhangs  310  that maintain the rod  304  within the guide channel  306 . One end of the guide channel  306  starts at a position adjacent to the side guide  212  when the side guide  212  is adjacent to the side frame  118  and extends in the direction indicated by the arrow  106  as shown in  FIG. 2 . The guide channel  306  ends at a position along the slide plate  202  in the direction indicated by the arrow  104 . By placing the rod  304  in the guide channel  306 , play can be reduced because the channel  306  limits the movement of the rod  304 . Play is also reduced because only one piece (i.e., the rod) has to be controlled. In other words, the motion of the side guide  212  is directly transmitted and rotated to the slide plate  202 . The actuator is also flexible so that it can conform to the geometry of the guide channel  306  and be less dependent on actual cassette geometry.  
         [0050]     Between the center of the rack and pinion connection  210  and the side frame member  166 , the guide channel  306  turns. As shown in  FIG. 2 , the guide channel  306  turns at turn  310  such that the motion of the guide channel  306  is linearly translated and rotated to the slide plate  202 . The radius in which the guide channel  306  turns is selected so that the rod  304  moves easily within the guide channel  310  and to efficiently use space within the cassette. In particular, the radius of the turn  310  is set at a minimum value so that the rod  304  can easily move at the turn  310  and to prevent the rod  306  from getting stuck in the guide channel  306 . Conversely, the radius of the turn  310  is set at a maximum value in order to efficiently use the space within the cassette  110 . As shown in  FIG. 2 , an approximate right angle is used. However, as should be appreciated, any angle can be used.  
         [0051]     As should be appreciated, the rod  304  can be made of any material currently available and later developed such that the rod  304  does not buckle within the guide channel  306 , while still flexible enough to move freely within the guide channel  306 . The rod  304  can also have any shape or cross section, including the “I” cross section as shown in  FIG. 4 . Furthermore, the rod  304  can be made of any material and can have any shape or cross section such that the play between the rod  304  and the guide channel  306  is minimized while allowing easy movement of the rod  304 .  
         [0052]     Thus, according to the present invention, sheet size sensing is greatly improved and reliability is improved because there is only one component (i.e., the rod) is used. Overall size sensing is also improved because substantially all detrimental tolerances that are created by multiple components is removed. Furthermore, overall size sensing is also improved because the relative motion between the guide member and slide plate is substantially eliminated.  
         [0053]     While this invention has been described in conjunction with various exemplary embodiments, it is to be understood that many alternatives, modifications and variations would be apparent based on the foregoing description. Accordingly, the exemplary embodiments of this invention, as set forth above are intended to be illustrative, and not limiting. Various changes can be made without departing from the spirit and scope of this invention.