Abstract:
An ink cartridge employable for an ink jet type recording apparatus includes a case ( 4 ) having a front plate ( 4   a ) with at least one position determining hole ( 4   h/   4   g ) formed therein. An ink bag ( 1 ) containing a supply of ink is received in the case ( 4 ) in a manner such that the position determining hole ( 4   h/   4   g ) allows the insertion of a position determining shaft ( 16/17 ) projecting from an inner end of a cartridge holder ( 90 ) through the position determining hole ( 4   h/   4   g ) to guide and properly locate the ink cartridge ( 80 ) relative to the cartridge holder ( 90 ) without establishing communication between the ink bag ( 1 ) and the position determining shaft ( 16/17 ). An ink outlet piece ( 2 ) having an ink flow path therein communicates with the ink bag ( 1 ) so that an ink feeding needle ( 15 ) disposed at the inner end of the cartridge holder ( 90 ) and slightly behind the position determining shaft ( 16/17 ) is capable of piercing through the ink outlet piece ( 2 ) to reach an interior of the ink bag ( 1 ), the outlet piece (2) being positioned to contact the ink feeding needle ( 15 ) after the ink cartridge ( 80 ) has been properly located relative to the cartridge holder ( 90 ) by the position determining hole ( 4   h,    4   g ) and the position determining shaft ( 16/17 ).

Description:
This is a Continuation-in-Part of parent application Ser. No. 08/295,040 now U.S. Pat. No. 5,666,146 filed Aug. 25, 1994, which is a Continuation Application of grandparent application Ser. No. 07/888,369 filed May 26, 1992 abandoned. The parent application Ser. No. 08/295,040 filed Aug. 24, 1995 is incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to an ink cartridge for use with an ink jet recording apparatus that performs a recording operation by jetting a series of ink droplets onto a recording paper through a nozzle. 
     Various kinds of ink feeding systems for an ink jet recording apparatus of the aforementioned type have been hitherto proposed and put to practical use. 
     To facilitate understanding of the present invention, a conventional ink cartridge having a flexible ink bag received therein and a mechanism for installing the ink cartridge will briefly be described below with reference to FIG.  7  and FIG.  8 . 
     The ink cartridge includes an ink bag a, and a tubular ink outlet piece b is integrated with the ink bag a by applying thermal fusion on one of the thermally fused sides (represented by hatched lines), thereby to allow ink in the ink bag a to be conducted to the outside through the ink outlet piece b. To fixedly hold the ink bag a at a predetermined position in a case e, the ink outlet piece b is provided with a pair of flanges c through which holes d are formed. Thus, the ink bag a can be positioned and fixedly received in the case e by fitting a pair of projections f on the front end part of the case e into the holes d. In addition, the ink cartridge includes a cover j which is placed on the opening of the case e. The cover j is integrated with the case e by thermally sealing the peripheral edge of the case e using an ultrasonic welding process. 
     A holder m having the case e received therein is fixedly mounted on an ink jet recording apparatus (not shown). The holder m includes a pair of frames n on the opposite sides thereof so as to guide slidable insertion of the ink cartridge h composed of the ink bag a and the case e. In addition, the holder m includes a pair of leaf springs p at the innermost end of the frame n. When ribs i on the opposite side walls of the ink cartridge h are engaged with the leaf springs p, the ribs i are fixedly retained by the leaf springs p. At this time, an ink feeding needle g projection from the ink jet recording apparatus is ready to pierce the central part of the ink outlet piece b. 
     With such construction, the positional relationship between the ink feeding needle g and the opposing pair of frames n, the positional relationship between the leaf springs p and the ribs i and the positional relationship between the case e and the ink outlet piece b are liable to be undesirably disturbed during steps of fitting and assembling. Thus, there is left unsolved a problem that the ink feeding needle g sometimes cannot be correctly located in alignment with the ink outlet piece b. 
     In addition, if the cover j is removed from the case e, it is difficult as a practical matter to reunite the former with the latter again such as by employing a thermal fusion process. For this reason, the ink cartridge h cannot repeatedly be used. Further, since the ink outlet piece b is secured to the thermally fused surfaces of the ink bag a, there is left unsolved another problem that a certain gap appears between the ink outlet piece b and the thermally fused surfaces. 
     SUMMARY OF THE INVENTION 
     Accordingly, an object of the present invention is to provide an ink cartridge for an ink jet recording apparatus wherein an ink outlet piece can be correctly aligned with an ink feeding needle regardless of a slight positional deviation from their preferred positions. 
     Another object of the present invention is to provide an ink cartridge for an ink jet recording apparatus wherein a case and a cover placed on the opening of the case can repeatedly be used. 
     According to one embodiment of the present invention, there is provided an ink cartridge assembly for an ink jet recording apparatus wherein the ink cartridge includes a fitting portion formed on a front plate of a case constituting the ink cartridge, the fitting portion serving to hold and locate an ink outlet piece in an engaged state by engaging the fitting portion with an engaging portion on the ink outlet piece and at least one position determining hole formed on the front plate of the case, the position determining hole serving to properly locate the ink cartridge relative to a cartridge holder by inserting a position determining shaft projecting from the inner end of the cartridge holder through the position determining hole. With such construction, the ink feeding needle can be correctly located in alignment with the ink outlet piece with the front plate of the case serving as a reference. 
     To assure that the case and the cover can repeatedly be used, engagement holes are formed on the front plate of the case positioned so as to engage with the corresponding corner portions disposed on the front edge of a cover, and engagement portions are formed on the opposite side plates of the case at the rear end of the same positioned so as to engage with the corresponding pawls disposed on the opposite sides of the cover at the rear end of the same, whereby the cover can be repeatedly fitted to the case in a snap fit fashion. 
     According to another embodiment of the present invention, there is provided an ink cartridge for an ink jet recording apparatus which also includes an absorbing member, disposed to be stacked with the ink bag in the case, for absorbing exhaust ink within the ink cartridge. There is also provided an exhaust ink take-in piece for supplying the exhaust ink to the inner end of the cartridge holder. 
     Other objects, features and advantages of the present invention will become apparent from reading of the following description which has been made in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a preferred embodiment of an ink cartridge for an ink jet type recording apparatus constructed in accordance with the present invention, particularly illustrating the structure of the ink cartridge in a disassembled state; 
     FIG. 2 is a cross-sectional view of an ink outlet piece to be secured to an ink bag; 
     FIG. 3 is a sectional view of a position determining/engaging mechanism for the ink outlet piece; 
     FIG. 4 is a perspective view of the ink cartridge and a holder, particularly illustrating the structure of the holder in a disassembled state; 
     FIG. 5 is a diagrammatic view schematically illustrating an ink flow passage system for the ink jet recording apparatus; 
     FIGS. 6 a - 6   c  are sectional views of the ink cartridge, particularly illustrating displacement of a detection plate in the ink cartridge; 
     FIG. 7 is a perspective view of a conventional ink cartridge, particularly illustrating the structure of the ink cartridge in a disassembled state; 
     FIG. 8 is a perspective view of the ink cartridge and a holder, particularly illustrating the structure of the holder; 
     FIG. 9 is an exploded view perspective of another embodiment of an ink cartridge for an ink jet type recording apparatus constructed in accordance with the present invention, particularly illustrating the structure of the ink cartridge in a disassembled state; 
     FIG. 10 is a plan view showing the side of the ink cartridge, which has ink takeout ports formed therein; 
     FIG. 11 is a cross sectional view showing the ink cartridge and the ink cartridge holder; and 
     FIG. 12 is a diagrammatic view schematically illustrating an ink flow passage system for the ink jet recording apparatus. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention will hereinafter be described in detail with reference to the accompanying drawings, which illustrate preferred embodiments of the present invention. 
     FIG. 1 is a perspective view which illustrates an ink cartridge for an ink jet recording apparatus and which is constructed in accordance with a preferred embodiment of the present invention, FIG. 2 is a cross-sectional view of an ink outlet piece to be fitted to an ink bag, and FIG. 3 is a partially sectioned view of a position determining/engaging mechanism for the ink outlet piece. 
     The ink bag designated by reference numeral  1  is constructed using a laminated aluminum film which is laminated with two films such that the outside of the ink bag is lined with, e.g., a nylon film, while the inside of the same is lined with, e.g., a polyethylene film in order to improve the gas barrier property of the ink bag. These films are thermally fused together along the outer peripheral edge of the ink bag  1 . 
     To conduct ink out of the ink bag  1  to the outside, an ink outlet piece  2  is integrated with the ink bag  1  by thermal fusion on the front side, as seen in FIG.  1 . The ink outlet piece  2  is molded of a plastic material. As shown in FIG. 2, the rear part of the ink outlet piece  2 , i.e., the joint location where the ink bag  1  is thermally fused with the ink outlet piece  2 , is constructed in a leaf-shaped configuration such that the central part exhibits an convex arc having a large radius of curvature and the opposite ends exhibit an concave arc having a large radius of curvature. With this construction, a gap between the ink bag  1  and the ink outlet piece  2  is fully filled with molten material during a thermal fusing operation to provide a reliable seal. 
     The forward half of the ink outlet piece  2  has a circular sectional shape, and an annular engagement groove  2   a  for holding the ink bag  1  at a predetermined position on a case  4  (similar to the position determining annular engagement groove  2  disclosed in commonly assigned Japanese Examined Patent Application Publication (Kokoku) No. 2-192953) is formed around the outer periphery of the ink outlet piece  2 . A fitting portion  4   b  of the case  4  is fitted into the engagement groove  2   a  (see FIG.  3 ). In addition, a chuck portion  2   b  is formed around the central part of the ink outlet piece  2  so as to facilitate grasping of the ink bag  1  during a step of automatically receiving the ink bag  1  in the case  4  on a mass production line. A tube portion  2   c  is formed along the center axis of the ink outlet piece  2  so as to conduct ink from the ink bag  1  to the outside. A sealing member  3  molded of an elastic material such rubber or the like is fitted into the forward end part of the ink outlet piece  2  so as to reliably maintain airtightness between the member  3  and an ink feeding needle  15  (to be described later). Further, a film portion  2   d  is interposed between the tube portion  2   c  and the sealing member  3  in order to prevent incorrect printing from being performed due to undesirable elution or deposition of the rubber caused by direct contact of the ink with the sealing member  3 . 
     The case  4  for receiving the ink bag  1  is designed in a box-shaped configuration having a small thickness. A fitting portion  4   b  having a semicircular recess to be engaged with the engagement groove  2   a  of the ink outlet piece  2  is formed on a front plate  4   a  of the case  4  in a snap-fit fashion. In addition, an opposing pair of position determining holes  4   g  and  4   h  are formed on the front plate  4   a  of the case  4  with the fitting portion located therebetween. As shown in FIG. 4, the case  4  is correctly held at a predetermined position as seen not only in the upward/downward direction but also in the leftward/rightward direction by inserting a position determining shaft  16  and a guide shaft  17  on a holder  9  into the position determining holes  4   g  and  4   h.    
     The ink bag  1  is firmly held in position in the case with the aid of a pressure-sensitive-adhesive double-sided tape (hereinafter referred to simply as an adhesive tape), and a detection plate  5 , of which the forward end is bent at a right angle, is adhesively attached to the upper surface of the ink bag  1  with the aid of an adhesive tape. As the quantity of the ink in the ink bag  1  decreases, the bent part  5   a  of the detection plate  5  is projected outside of a rectangular hole  4   i  at the lower part of the case  4 , whereby a so-called “near-end” state of the ink can be detected by an ink end detector  11 , as shown in FIG.  6 . 
     A cover  6  placed on the opening portion of the case  4  includes a pair of corner portions  6   a  along the front edge thereof, and a pair of pawls  6   b  on the opposite sides at the rear end thereof. Thus, the cover  6  can be firmly fitted to the case  4  in a snap-fit fashion by inserting the corner portions  6   a  into holes  4   d  on the front plate  4  of the case  4  and then fitting the pawls  6   b  into recesses  4   e  on side plates  4   c  of the case  4  at the rear part of the same. When the cover  6  is to be removed from the case  4 , it is recommended to insert a jig or other tool into a cutout  4   f  on a rear plate  4   j  of the case  4  and then pry off the cover  6 . 
     A label  7  having a caution instruction or the like printed thereon is adhesively arranged on the cover  6  in such a manner as to hide the cutout  4   f  from the outside. This arrangement prevents not only dislodgment of the cover  6  from the case  4  due to vibration or careless dropping, but also intentional opening of the cover  6 . 
     According to a modified embodiment of the present invention, an ink cartridge may be constructed such that the corner portions  6   a  and the pawls  6   b  on the cover  6  are eliminated and the cover  6  is firmly held merely by the label  7 . In this embodiment, it is necessary that the label  7  be adhesively placed on the case  4  while extending from the front plate  4   a  to the rear plate  4   j  of the case  4 . With this construction, the ink cartridge can be provided at a more inexpensive cost. 
     Next, a mechanism for installing an ink cartridge  8  in an ink jet recording apparatus will be described below with reference to FIG.  4 . 
     A holder  9  is fixedly mounted on the ink jet recording apparatus I (not shown). To assure that the ink cartridge  8  is correctly received in the holder  9  and then firmly held at a predetermined position on the holder  9 , an opposing pair of frames  10  are arranged for constructing the holder  9 . In addition, a shutter  12  is arranged so as to prevent the ink feeding needle  15  projecting into the interior of the holder  9  to touch the user&#39;s hand when the ink cartridge is received in the holder  9 . The shutter  12  is turnably supported on the holder  9  to turn about a rotational center axis  12   a  so that it normally assumes the position shown by the action of a shutter spring (not shown). While the shutter is in the position shown, it is engaged with pawls of elastically deformable lock arms  10   a  disposed along the lower edges of the frames  10 . 
     The forwardmost end of each of the lock arms  10   a  normally projects into a guide groove  10   b  extending along the lower edge of the frame  10 . Thus, when the ink cartridge  8  is inserted midway between both the frames  10 , the lock arms  10   a  are squeezed by ribs  4   k  on the opposite sides of the cast  4  at the forwardmost end of the same so that they are displaced from the engaged state. 
     Leaf springs  13  arranged at the innermost ends of the opposing pair of frames  10  project into the region where the ink cartridge  8  is to be received. When the ink cartridge  8  is inserted and reaches the innermost end of the holder  9  while being guided by a position determining shaft  16  and a guide shaft  17 , the leaf springs  13  engage with the ribs  4   k  on the case  4 , whereby the ink cartridge  8  is firmly held in place. 
     As is best seen in FIG. 4, the ink feeding needle  15  disposed at the innermost end of the cartridge  9  projects toward the ink cartridge  8  at the position where it is located slightly behind the position determining shaft  16  and the guide pin  17 . Thus, when the ink cartridge  8  is firmly retained by the leaf spring  13 , the ink feeding needle  15  pierces through the sealing member  3  and the ink outlet piece  2  to reach the interior of the ink bag  1 . 
     In FIG. 4, reference numeral  4   w  designates ribs which are formed on the opposite side of the case  4  at the rearmost end of the same so as to prevent erroneous insertion of the ink cartridge  8 . If the ink cartridge  8  is inserted in the reverse direction by mistake, the ribs  4   w  collide with erroneous insertion preventing projections  10   c  on the frames  10 , making it impossible for the ink cartridge  8  to be inserted into the holder  8  any further. 
     FIG. 5 is a diagrammatic view which illustrates an ink flow passage system for the ink jet recording apparatus. 
     As shown in the drawing, a filter  21  is arranged on the left-hand end surface of the holder  9  for preventing dust or other foreign material from entering the ink flow passage system. The ink feeding needle  15  is connected to a printing head  18  via the filter  21  and an ink feeding tube  19 . 
     In FIG. 5, reference numeral  24  designates a cap disposed outside of a non-printing region. The cap  24  communicates with a waste liquid bag  26  via a waste liquid tube  22  and a pump  23 . When a printing head  18  returns to a waiting position, the cap  24  comes into contact with the nozzle surface of the printing head  18  so that ink remaining in the printing head  18  is recovered in a waste liquid absorbing material  27  in the waste liquid bag  26  so as to prevent the printing head  18  from being clogged with used ink when the ink jet recording apparatus is held in an inoperative state. 
     Next, the installation of the ink cartridge  8  constructed in the above-mentioned manner will be described below. 
     The ink outlet piece  2 , the rear half of which has a leaf-shaped cross-sectional contour, can be secured to the upper and lower films of the ink bag  1  by thermal fusion not only without any gap therebetween but also without large warpage thereof. 
     When the ink bag  1  is received in the case  4 , the forward half of the ink outlet piece  2  projecting outside of the ink bag  1  is located in alignment with the front plate  4   a  of the case  4  so as to allow the engagement groove  2   a  of the ink outlet piece  2  to be engaged with the fitting portion  4   b  at the central part of the front plate  4   a . Thus, the ink bag  1  is located and received at a predetermined position on the case  4  while the front plate  4   a  of the case  4  serves as a reference. 
     Next, the detection plate  5  is adhesively placed on the upper surface of the ink-bag  1  using adhesive tape, and thereafter the cover  6  is placed on the case  4 . At this time, while the corner portions  6   a  on the front edge of the plate  4   a  of the case  4 , the rear end part of the cover  6  is depressed with an user&#39;s hand, causing the pawls  6   b  on the opposite sides of the case  4  at the rear end of the same to be engaged with the recesses  4   e  on the side plates  4   c  of the case  4 . Consequently, the cover  6  is firmly fitted into the opening of the case  4  in the snap-fit fashion. 
     When the ink cartridge  8  assembled in the above-described manner is received in the holder  9 , the ink cartridge  8  having the ink outlet piece  2  located ahead thereof is inserted into the holder  9  by sliding the same along the guide grooves  10   b  of the frames  10 . As the ribs  4   k  are slidably displaced in this manner, first they deflect the lock arms  10   a  in the outward direction so as to allow the shutter  12  to be released from the engaged state. Then, the ink cartridge  8  turns the shutter in the upward direction, whereby it is introduced into the holder  9 . 
     When the ink cartridge  8  is inserted to a position in the vicinity of the innermost end of the holder  9 , the position determining shaft  16  and the guide shaft  17  horizontally projecting toward the front plate  4   a  of the case  4  are inserted through the corresponding holes  4   g  and  4   h  on the front plate  4   a  of the case  4  so that the ink cartridge  8  is correctly received in the holder  9  not only in the upward/downward direction but also in the leftward/rightward direction. 
     Subsequently, when the ink cartridge  8  is squeezed further to contact the innermost end of the holder  9  with the aid of the position determining shaft  16  and the guide shaft  17 , the ink feeding needle  15  projecting from the innermost end of the holder  9  pierces the sealing member  3  and the film portion  2   d  so as to be inserted into the ink bag  1 . At this point, the ink contained in the ink bag  1  is ready for use. 
     Another embodiment of the invention will be described with reference to FIGS. 9 through 12. 
     FIG. 12 is a diagram schematically showing an overall ink passage (ink flow) system of an ink jet printing apparatus into which an ink cartridge embodying the present invention is incorporated. An ink cartridge  80  is held by a holder  90 . Ink is led out of an ink bag  1  contained in the holder  90 , by way of an ink supplying needle  15 . A filter  21  is connected to the output of the ink supplying needle  15 . The filter  21  filters out dust and other foreign materials from the supplied ink. The output of the filter  21  is connected to an ink supplying tube  19 . 
     The ink supplying tube  19  supplies ink to a print head  18  held by a carriage, not shown. The print head  18  is reciprocatively moved in the lengthwise direction of a platen  20  while being held by the carriage. The print head  18  prints on a sheet of paper, not shown, placed on the platen  20 . A combination of a cap  24  and a pump  23  are provided for maintaining good quality print by the print head  18 . The cap/pump combination performs the cleaning (wiping) of the ink jet nozzles of the print head  18  and the sucking of waste ink. The cap  24  and the pump  23  are interconnected by a waste ink tube  22 . Waste ink is sucked by the pump  23  through the waste ink tube  22 , and supplied to a waste ink collecting portion (absorbing member  100 ) to be described later, contained in the ink cartridge  80 , by way of a waste ink needle  25 . 
     FIG. 9 is an exploded view perspective of an ink cartridge according to the present embodiment. FIG. 10 is a plan view showing the side of the ink cartridge, which has ink takeout ports formed therein. In those figures, like or equivalent portions are designated by like reference numerals used in FIG.  1 . 
     A rectangular wall  61  is provided on the reverse side of a cover  6 . An absorbing member  100  made of pulp is mounted on the inner side of the wall  61 . The mounted absorbing member  100  forms the waste ink collecting portion, referred to above, within the ink cartridge  80 . The wall  61  is provided with an inlet rubber  62  into which the waste ink needle  25 , to be described in detail further below, is inserted. A hole  4   z  is formed in a front plate  4   a  of the ink cartridge  80 . 
     FIG. 11 illustrates how the ink cartridge  11  is attached to the ink jet printing device. FIG. 11 is a cross sectional view showing a structure including the ink cartridge  80  and the holder  90  that holds the ink cartridge  80 . 
     Guide means  92  are provided on the upper and lower sides of the holder  90 . The guide means  92  are fixed to the ink jet printing device (not shown), and function to guide the insertion of the ink cartridge  80  and to hold the ink cartridge  80  in place. A bottom wall  93  is provided on the deepest side of the holder  90 , while interconnecting the upper and lower guide means  92 . A couple of guide shafts  16  and  17 , the ink supplying needle  15  made of metal, a base  99  for fixedly supporting the ink supplying needle  15 , the waste ink needle  25 , and wall  91  for defining the insertion direction of the ink cartridge  80  stand erect on the bottom wall  93 . The guide means  92 , bottom wall  93 , guide shafts  16  and  17 , waste ink needle  25 , and wall  91  are plastic molded into a one-piece construction. On the reverse side of the bottom wall  93 , the ink supplying needle  15  is connected to the ink supplying tube  19 , and the waste ink needle  25  is connected to the waste ink tube  22 . 
     The ink cartridge  80  is moved in the direction of an arrow D for its insertion while being guided by the guide means  92 . When the ink cartridge is further inserted beyond the position illustrated, the guide shafts  16  and  17 , which extend upward from the bottom wall  93 , are respectively inserted into a position determining hole  4   h  and a position determining hole  4   g . As a result, the ink cartridge  80  is vertically and horizontally positioned within the holder  90 . The tips of the guide shafts  16  and  17  are tapered so as to the guide shafts to smoothly be inserted into the position determining holes  4   h  and  4   g . The heights of the guide shafts  16  and  17 , ink supplying needle  15  and waste ink needle  25  are selected so that the waste ink needle  25  does not reach the inlet rubber  62 . The coupling of the guide shafts  16  and  17  with the position determining holes  4   h  and  4   g  positions the ink cartridge  80  with respect to the ink supplying needle  15  and the waste ink needle  25 . 
     When the ink cartridge  80  further advances, the ink supplying needle  15  breaks through an outlet rubber  3  and the ink outlet piece  2 , wherein the outlet rubber  3  is fitted into the forward end part of the ink outlet piece  2  as illustrated in FIG. 3, and reaches the waste ink collecting portion (absorbing member  100 ) surrounded by the rectangular wall  61  within the ink cartridge  80 . 
     Finally, the front plate  4   a  of the ink cartridge  80  is abutted against the wall  91  that surrounds the base  99 , and fixed thereat by locking means, not shown. In this state, the ink bag  1  in the ink cartridge  80  communicates with the print head  18  through the ink supplying tube  19 , and the waste ink collecting portion (absorbing member  100 ) is connected to the waste ink tube  22 . The outlet rubber  3  tightly contacts with the side surface of the waste ink needle  25 , whereby no ink is leaked out of the waste ink collecting portion (absorbing member  100 ). 
     To detach the ink cartridge  80 , the locking means is unlocked and the ink cartridge  80  is moved in the direction that is reverse to the direction D. The ink supplying needle  15  and the waste ink needle  25  are pulled out of the outlet rubber  3  and the inlet rubber  62 , and then the guide shafts  16  and  17  are disengaged from the position determining holes  4   h  and  4   g . The ink cartridge  80  is guided by the guide shafts  16  and  17 , and moves along and parallel to the ink supplying needle  15  and the waste ink needle  25 . Therefore, in detaching the ink cartridge  80 , an desired vertical force is prevented from being exerted on the ink supplying needle  15  and waste ink needle  25 . 
     In the present embodiment, the waste ink needle  25  is made of plastic since it and the holder  90  are plastic molded into a one-piece construction. Alternatively, the waste ink needle  25 , like the ink supplying needle  15 , may be made of metallic material. 
     While the present invention has been described above with respect to preferred embodiments, various changes and modifications may be made without departure from the scope of the present invention as defined by the appended claims.