Patent Publication Number: US-6655785-B1

Title: Print element and method for assembling a print head

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a print element for a thermal ink jet printing apparatus and, more particularly, to a print element which can be used in different printing apparatus and with different types of ink supplies. 
     2. Prior Art 
     U.S. Pat. Nos. 5,297,336 and 5,519,425 disclose an ink manifold formed with an ink supply into a unitary ink supply cartridge for a thermal ink jet printer. U.S. Pat. No. 4,695,854 discloses an external manifold for an ink jet array. 
     SUMMARY OF THE INVENTION 
     In accordance with one embodiment of the present invention a print element is provided comprising a heat sink, a printed wiring member, a thermal ink jet assembly, and a manifold assembly. The printed wiring member is mounted on the heat sink. The thermal ink jet assembly is mounted to the heat sink. The manifold assembly is connected to the heat sink and the thermal ink jet assembly. The manifold assembly comprises a first mount for removably connecting a first source of ink to the manifold assembly and a first outlet to the thermal ink jet assembly. 
     In accordance with another embodiment of the present invention a print head is provided comprising a housing and a print element. The housing has a receiving area for removably receiving at least one ink tank. The print element is connected to the housing and has a heat sink, a thermal ink jet assembly, and a manifold assembly. The manifold assembly has at least one mount for removably connecting the ink tank to the manifold assembly. The housing has an aperture. The manifold assembly extends through the aperture. 
     In accordance with another embodiment of the present invention, a print head assembly is provided comprising a carriage and two print heads connected to the carriage. Each print head has a housing and a print element connected to the housing. Each print element has a heat sink and an ink manifold assembly mounted to the heat sink and an ink jet assembly. A portion of the ink manifold assemblies are located in their respective housing receiving areas and the heat sinks are located at exterior sides of the housings and located between the two housings. 
     In accordance with one method of the present invention a method of manufacturing ink jet printing components is provided comprising steps of assembling a print element and optionally connecting the print element to a print head housing. The method of assembling a print element comprises steps of connecting a thermal ink jet assembly to a heat sink; connecting a printed wiring member to the heat sink; and connecting an ink manifold assembly to the heat sink and the thermal ink jet assembly. The print head housing has a receiving area for removably receiving an ink tank. The print element can be assembled in a first type of printing device without the print head housing and, a combined assembly of the print element and the print head housing can be assembled in a second type of printing device. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The foregoing aspects and other features of the present invention are explained in the following description, taken in connection with the accompanying drawings, wherein: 
     FIG. 1 is a perspective view of a print head assembly comprising features of the present invention; 
     FIG. 2 is an exploded perspective view of one of the print heads used in the assembly shown in FIG. 1; 
     FIG. 3 is an exploded perspective view of the print element shown in FIG. 2; 
     FIG. 4 is an exploded perspective view of the ink manifold assembly used in the print element shown in FIG. 3; 
     FIG. 5 is an exploded perspective view of the other print head used in the assembly shown in FIG. 1; 
     FIG. 6 is an exploded perspective view of the print element shown in FIG. 5; 
     FIG. 7 is an exploded perspective view of the ink manifold assembly used in the print element shown in FIG. 6; 
     FIGS. 8A and 8B are schematic diagrams of methods of using a same type of print element in two different types of printing devices; 
     FIG. 9 is a schematic perspective view of three print elements being grouped or ganged together in a staggered or stepped configuration; 
     FIG. 10 is an exploded perspective view of an alternate embodiment of a print head having a dual ink manifold assembly; and 
     FIGS. 11-13 schematic diagrams of examples of alternate embodiments of how print elements can be grouped. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 1, there is shown a perspective view of a print head assembly  10  incorporating features of the present invention. Although the present invention will be described with reference to the embodiments shown in the drawings, it should be understood that the present invention can be embodied in many alternate forms of embodiments. In addition, any suitable size, shape or type of elements or materials could be used. 
     The print head assembly  10  generally comprises a carriage  12  and two print heads  14 , 16  mounted to the carriage  12 . The carriage  12  is intended to be movably mounted on a frame of a printing device, such as a thermal ink jet printer, for reciprocating lateral sliding movement on the frame as is generally known in the art. In this embodiment the first print head  14  is intended to be a black ink print head and the second print head  16  is intended to be a color ink print head. However, in the alternate embodiments, the print head assembly configuration could be varied, such as a carriage with only a single black ink print head, a carriage with multiple black ink print heads, a carriage with multiple color print heads, or any other suitable configuration. 
     Referring also to FIG. 2, the first print head  14  generally comprises a housing  18 , a print element  20 , and a seal member  22 . The housing  18  is preferably a one-piece molded plastic member. In this embodiment the housing  18  comprises a receiving area  24 , an integrally formed resilient latch  26 , substantially open top and front ends, and an aperture  28  extending through the housing. The receiving area  24  is suitably sized and shaped to removably receive an ink supply cartridge or tank  30 . The tank  30  can be inserted into and removed from the receiving area  24  through the substantially open top and front ends of the housing  18 . The latch  26  is configured to resiliently snap-lock latch the tank  30  inside the receiving area  24 . The latch  26  can deflect in a general cantilever fashion. A user can deflect the top end of the latch  26  rearward for removing or unlatching the tank  30  from the housing  18 . In alternate embodiments any suitable type of latching or mounting mechanism could be used to fix the tank  30  with the housing  18 . In this embodiment the aperture  28  extends through a corner of the housing  18 ; through portions of the bottom wall  32  and the right side wall  34 . However, in alternate embodiments the aperture could extend merely through the bottom wall  32  or through any one or more of the side walls of the housing  18 . 
     Referring also to FIG. 3, the print element  20  generally comprises a heat sink  36 , a printed wiring member  38 , a thermal ink jet assembly  40 , an ink manifold assembly  42 , a fluid seal  44 , and a facetape  46 . In this embodiment the print elements have thermal ink jet assemblies. However, features of the present invention could be used without a heat sink and with a piezoelectric ink jet assembly, an acoustic ink jet assembly, a thermal wax printer, or any other suitable liquid ink printing device. The heat sink  36  is preferably a flat one-piece member, such as aluminum. The printed wiring member  38  includes electrically conductive traces on a substrate with contact pads  48  at one end and contact areas  50  at an opposite end. The printed wiring member  38  is fixedly attached directly on the heat sink  36  with the contact pads  48  at a rear end edge and the contact areas  50  at a bottom end edge. Thus, the member  38  has a general right angle or L-shaped configuration. The rear end of the heat sink  36  and the contact pads  48  are sized and shaped to be connected to an electrical connector, similar to a card edge connector, such as disclosed in U.S. Pat. No. 4,934,961 which is hereby incorporated by reference, but as a single row of contacts on one side of the card edge receiving area. However, any suitable electrical connection could be made. The member  38  also has holes therethrough for mounting posts of the ink manifold assembly  42  to extend through. The posts can extend into holes in the heat sink  36  for mounting the ink manifold assembly  42  to the heat sink  36 . The thermal ink jet assembly  40  is fixedly attached to the side of the heat sink  36  at its bottom end edge. The ink jet assembly  40  is also operably connected to the contact areas  50  of the printed wiring member  38 . The fluid seal  44  covers a side of the ink manifold assembly  42  and has slots  52  for ink to flow from an outlet of the ink manifold assembly  42  to the ink jet assembly  40 . In the embodiment shown, the printed wiring member  38 , ink jet assembly  40 , and ink manifold assembly  42  are mounted to one side  36   a  of the heat sink  36 . In an alternate embodiment mirror image components of these members  38 ,  40 ,  42  (or their equivalent) could be mounted to the opposite side  36   b  of the heat sink  36 . Thus, the contact pads  48  could be located at a first location (on side  36   a ) or optimally located at a second different location (on side  36   b ). In another alternate embodiment, two sets of the members  38 ,  40 ,  42  could be mounted to the one member  36 ; one set on each side  36   a ,  36   b.    
     Referring also to FIG. 4, the ink manifold assembly  42  generally comprises a base member  54 , a cover  56 , and two filters  58 ,  60 . The base member  54  and cover  56  are preferably comprised of molded plastic. The base member  54  generally comprises a first section  62  and a second section  64 . The first section  62  includes mounting post  66  (only one of which is shown), a recess  68  for receiving and supporting the ink jet assembly  40 , and an outlet  70  through the first section  62 . The second section  64  extends generally perpendicularly from the first section  62 . The second section  64  has an ink well  72  which receives the first filter  58  and is in communication with the outlet  70 . The cover  56  is mounted on the second section  64  with the first filter  58  being sandwiched therebetween. The cover  56  includes a mount  74  extending upward from its top side. The second filter  60  is mounted inside the mount  74 . The second filter  60  is a coarser filter then the first filter  58 . The mount  74  is sized and shaped to extend into a receiving hole  76  in the ink tank  30 (see FIG.  2 ). The mount  74  is also suitably sized and shaped to have a hose or conduit (not shown) from a different type of ink supply mounted thereon around the outer perimeter of the mount. The mount  74  extends generally parallel relative to the heat sink  36 . 
     In order to form the first print head  14  the print element  20  is manufactured and then connected to the housing  18 . The housing  18  has mounting posts (not shown) on the exterior of its right side that extend into holes of the heat sink  36  and mount the heat sink  36  on the exterior of the right side of the housing  18 . The ink manifold assembly  42  extends through the aperture  28  into the receiving area  24 . The seal member  22  is placed against the interior bottom wall  32  of the housing  18  with the mount  74  extending through the hole  78  (see FIG.  2 ). The seal member  22  is preferably comprised of an elastomeric material and includes a resilient upwardly facing ridge  80 . The ridge  80  functions as a spring. The ridge  80  is resiliently compressed or deflected when the tank  30  is inserted into the receiving area  24  and helps to distribute some of the mounting load, from the tank  30  being placed into the receiving area  24 , onto the housing  18  rather than all of the load being placed against the mount  74  and the print element  20 . The spring feature of the ridge  80  also biases the ink tank  30  towards the latch  26  to stabily hold the tank  30  with the print head  14  with minimal forces being exerted against the print element  20  and the otherwise undesired resultant movement of the ink jet assembly  40 , during ink tank loading. 
     Referring to FIGS. 1 and 5, the second print head  16  generally comprises a housing  118 , a print element  120 , and a seal member  122 . The housing  118  is preferably a one-piece molded plastic member. In this embodiment the housing  118  comprises a receiving area  124 , three integrally formed resilient latches  126 , substantially open top and front ends, and an aperture  128  extending through the housing. The receiving area  124  is suitably sized and shaped to removably receive three ink supply cartridges or tanks similar to the black ink tank  30 , but smaller in width and having color inks. The tanks can be inserted into and removed from the receiving area  124  through the substantially open top and front ends of the housing  118 . The latches  126  are configured to resiliently snap-lock latch the tanks inside the receiving area  124 . The latches  126  can deflect in a general cantilever fashion. A user can manually deflect the top end of the latches  126  rearward for removing or unlatching the tanks from the housing  118 . In alternate embodiments any suitable type of latching or mounting mechanism could be used to fix the tanks with the housing  118 . In this embodiment the aperture  128  extends through a corner of the housing  118  and through portions of the bottom wall  132  and the left side wall  133 . However, in alternate embodiments the aperture could extend merely through the bottom wall  132  or through any one or more of the side walls of the housing  118 . 
     Referring also to FIG. 6, the print element  120  generally comprises a heat sink  136 , a printed wiring member  138 , a thermal ink jet assembly  140 , an ink manifold assembly  142 , a fluid seal  144 , and a facetape  146 . The heat sink  136  is preferably a flat one-piece member, such as aluminum. 
     Preferably, the heat sink  136  is exactly the same as the heat sink  36 , but could be different. The printed wiring member  138  includes electrically conductive traces on a substrate with contact pads at a rear end and contact areas at an opposite bottom end. The printed wiring member  138  is fixedly attached directly on the heat sink  136  with the contact pads at a rear end edge and the contact areas at a bottom end edge. Thus, the member  138  has a general right angle or L-shaped configuration. The rear end of the heat sink  136  and the contact pads of the member  138  are preferably designed to have a card edge type of electrical connector removably mounted thereon similar to the heat sink  36  and contact pads  48 . In an alternate embodiment a single electrical connector can be mounted on the rear end of both heat sinks  36 ,  136  and electrically connected to both sets of contact pads. The member  138  also has holes therethrough for mounting posts of the ink manifold assembly  142  to extend through. The posts can extend into holes in the heat sink  136  for mounting the ink manifold assembly  142  to the heat sink  136 . The thermal ink jet assembly  140  is fixedly attached to the side of the heat sink  136  at its bottom end edge. The ink jet assembly  140  is also operably connected to the contact areas of the printed wiring member  138 . The fluid seal  144  covers a side of the ink manifold assembly  142  and has slots  152  for ink to flow from outlets of the ink manifold assembly  142  to the ink jet assembly  140 . 
     Referring also to FIG. 7, the ink manifold assembly  142  generally comprises a base member  154 , a cover  156 , and two types of filters  158 ,  160 . The base member  154  and cover  156  are preferably comprised of molded plastic. The base member  154  generally comprises a first section  162  and a second section  164 . The first section  162  includes mounting post  166 , a recess  168  for receiving and supporting the ink jet assembly  140 , and three outlets  170   a ,  170   b ,  170   c  through the first section  162 . The second section  164  extends generally perpendicularly from the first section  162  with three ink wells  172   a ,  172   b ,  172   c  which receive the filters  160  and are in communication with the outlets  170 . The cover  156  is mounted on the second section  164  with the filters  160  being sandwiched therebetween. The cover  156  includes three mounts  174   a ,  174   b ,  174   c  extending upward from its top side. The filters  158  are mounted inside the mounts  174 . The filters  158  are coarser filters than the filters  160 . The mounts  174  are sized and shaped to extend into a receiving hole in the ink tanks (similar to FIG.  2 ). The mounts  174  are also suitably sized and shaped to have a hose or conduit (not shown) from a different type of ink supply mounted thereon around the outer perimeter of the mounts. The mounts  174  extends generally parallel relative to the heat sink  136 . 
     In order to form the second print head  16  the print element  120  is manufactured and then connected to the housing  118 . The housing  118  has mounting posts  119  on the exterior of its left side  133  that extend into holes of the heat sink  136  and mount the heat sink  136  to the exterior of the left side of the housing  118 . The ink manifold assembly  142  extends through the aperture  128  into the receiving area  124 . The seal member  122  is placed against the interior bottom wall of the housing  118  with the mounts  174  extending through holes  178 . The seal member  122  is preferably comprised of an elastomeric material and includes a resilient upwardly facing ridge  180 . The ridge  180  functions as a spring. The ridge  180  is resiliently compressed or deflected when the tanks are inserted into the receiving area  124  and helps to distribute some of the mounting load, from the tanks being placed into the receiving area  124 , onto the housing  118  rather than all of the load being placed against the mounts  174  and the print element  120 . The spring feature of the ridge  180  also biases the ink tanks towards the latches  126  to stabily hold the tanks with the print head  16  with minimal forces being exerted against the print element  120  and the otherwise undesired resultant movement of the ink jet assembly  140 , during ink tank loading. In this embodiment the housing  118  also has notches  129  in its right side  134 . The distal end  165  of the manifold assembly  142  had projections  167 . When the print element  120  is mounted to the housing  118 , the projections  167  extend into the notches  129  to stabily mount the distal end  165  to the housing  118 . 
     Referring back to FIG. 1, the first print head  14  is positioned on the left side of the carriage  12  and the second print head  16  is positioned on the right side of the carriage  12 . The two heat sinks  36 ,  136  are, thus, located next to each other between the two housings  18 ,  118  under the section  13  of the carriage  12 . The heat sinks  36 ,  136  can be directly connected to each other or, alternatively, connected to a portion of the carriage  12  which is sandwiched directly between the two heat sinks  36 ,  136 . This provides the advantage of precisely locating the two print elements  20 ,  120  relative to each other even though they are two separate members and have their own separate and spaced ink tank receiving housings  18 ,  118 . In a preferred embodiment the connection of the two print elements  20 ,  120  to each other is staggered or stepped relative to the front of the carriage  12  to provide a precise offset D, such as the length of  110  ink jets, between the front ends of the ink jet assemblies  40 ,  140 . However, in alternate embodiments the offset D need not be provided or any suitable offset distance could be provided. In an alternate embodiment, the print element could be designed to have four ink tanks connected to it (one black and three color) and/or only one housing which can hold four or more ink tanks. The black ink could be replaced by three ink tanks; red-green-blue or low density inks for photographic printing. Thus, two of the three color print elements  120  could be used in a single device. 
     Referring now to FIG. 8A, the print element  20  can be used in a first type of printing device  200  without connecting the print element  20  to the housing  18 . For example, the first type of printing device  200  could have an ink supply  202  which is spaced from the print element  20  and connected to the mount  74  by a supply conduit or tube  204 . FIG. 8B illustrates that the same type of print element  20  can be mounted with the housing  18  at step  206  to form the print head  14  which is subsequently used to form the second different type of printing device  208  which can use rechargeable ink tanks mounted directly on the mount  74 . During the assembly process at the manufacturing facility, the print head  20  can be manufactured on an assembly line and, with the additional optional additional step of mounting the housing  18  to the print element  20 , the single assembly line can manufacture two different types of components for two different types of printing devices having different types of ink supply systems, but which use the same type of print elements. The present invention, by keeping the ink manifold assembly only on the print element and not using the housing  18  as part of the ink manifold, allows the print element to be tested and discarded if defective before connected to the housing  18 . Thus, if the print element is defective, a housing  18  does not also need to be discarded because the housing has not been connected to the print element yet. The present invention could also include the print element being permanently attached to an ink supply with an integral housing to form a unitary ink supply and print head cartridge similar to the cartridge disclosed in U.S. Pat. No. 5,519,425. The same multiple use/configuration described above for the black ink print element  20  is equally applicable to the color ink print element  120 . 
     Referring now to FIG. 9, three of the print elements  20  are shown in a gang or grouped configuration. The three print elements  20  are mounted on a carriage  12 ′ with the leading ends of their ink jet assemblies offset in a stepped configuration from the front edge of the carriage  12 ′. The mounts  74  would be connected to a single black ink source by three conduits (not shown). This type of ganging of the print elements  20  could be used in a device such as a plotter that prints on very large print medium, wherein ganging of the print elements in a stepped configuration can cover a larger area of the print medium in a single pass and thereby speed up printing. In alternate embodiments more or less than three of the same types of print elements can be ganged together, multiple gangs could be mounted on the same carriage, a print element and a gang or gangs of print elements could be on the same carriage, or multiple sets of one or more gangs of print elements could be on the same carriage. Any suitable grouping or configurations could be provided. Multiple carriages could also be provided. Some examples of these alternate embodiments are shown in FIGS. 11,  12 , and  13 . In FIG. 11, for example, the carriage  400  comprises three assemblies or gangs  402 ,  404 ,  406 . The three gangs  402 ,  404 ,  406  each have three print elements  408 ,  409 ,  410 ;  411 ,  412 ,  413 ; and  414 ,  415 ,  416 . The print elements  408 - 416  could be the same or different and could be connected to same color inks or grouped for connection to same color inks. For example, all the print elements  408 - 416  could be connected to one or more black ink sources. As another example, print elements  408 ,  411 ,  414  could be connected to one or more black ink sources and the rest of the print cartridges could be connected to color ink sources. As another example, the print elements in gang  402  could be connected to one color ink source, the print elements in gang  404  could be connected to a different color ink source, and the print elements in gang  406  could be connected to another different color ink source. FIG. 12 shows another example wherein a carriage  420  has an assembly or gang  422  of three print elements  424 ,  425 ,  426  and a print element  428  not directly ganged with the assembly  422 . FIG. 13 shows another example wherein the carriage  430  has two assemblies  432 ,  434 . Each assembly has two sub-assemblies  436 ,  438  and  440 ,  442 , respectively. Each sub-assembly has one or more print element. These embodiments help to illustrate the modularity aspect of the print elements of the present invention. The printing device could also have more than one carriage. 
     Referring now to FIG. 10 an alternate embodiment of the black ink print head  300  is shown. In this embodiment the print head  300  includes a combined ink tank receiving housing and ink manifold member  302 , a heat sink  304 , a manifold cover  306 , a coarse filter  308 , a seal  310 , an ink jet assembly  312 , a printed wiring member  314 , a fine filter  316 , a manifold filter cover  318 , and a faceplate  320 . In this embodiment the ink tank  30  is mounted in the member  302  and ink is conduited through the member  302 , to the fine filter  316  and manifold filter cover  318  on the opposite side of the heat sink  304 . The ink is then delivered to the ink jet assembly  312 . The ink jet assembly  312  is located on the opposite side of the heat sink  304  from the member  302 . Thus, forces from loading the ink tank  30  into the member  302  are not directly transferred to the ink jet assembly  312 . In addition, with this design heat can be stored in the ink and removed with drop ejection. With this type of design the ink jet assemblies could be located almost adjacent each other with only the manifold filter covers therebetween. This embodiment describes an ink jet cartridge which is made by joining two manifolds  318 ,  302 . There are multiple purposes and advantages for the two manifold approach. The primary one is that the first manifold  318  can be placed on each die and different versions of the second manifold  302  can be designed for different product families. Also, the precision molded features can be contained in the smaller first manifold, thus providing tolerance relief and wider materials choice for the second larger manifold. An advantage is the ability to print test the die with the first manifold to find rejects before final assembly begins. 
     In the two manifold design, the ink tanks are inserted into the port manifold. The printer carriage rigidly holds the heat sink on the datums. Previous designs place the manifold against the die and heat sink with two point contact on the fluid seal and the third point on the manifold. This ensures that the fluid seal is properly compressed against the die and therefore provides a good seal. Ink tank insertion therefore applies stress to the fluid seal bond. The dual manifold design isolates the ink tank insertion to the heat sink side opposite the die  312  and, therefore, none of the ink tank insertion forces are applied to the fluid seal. 
     Also, since the fluid seal compression is not an issue with the port manifold, the port manifold can be grounded against the heat sink creating a more rigid package. 
     Due to the fine filter manifold small size, the part can be placed more accurately with smaller tolerances in the critical fluid seal area. The port manifold is added after the print element assembly is cured and therefore the port manifold does not see the high temperature cure cycles. 
     The ink jet fluid path has many requirements such as ink compatibility, flatness, low thermal expansion, and high deformation temperature that severely limit the material selection. The single manifold approach can require a large housing to be made from an expensive material that is difficult to process, which makes the molds extremely expensive and difficult to maintain. The overall part size makes it difficult to maintain the critical features. The dual manifold approach passes most of the requirements to the fine filter manifold. This manifold has the flatness and low thermal expansion requirements in the fluid seal area, and goes through the high temperatures required to cure the fluid seal. The two manifold approach actually eases the design requirements because the part is small and therefore a lot easier to hold the tight tolerances. The port manifold only has the ink compatibility requirement, and therefore has more material options, including materials that are 4-5 times cheaper per pound and a lot easier to process making the mold cheaper. 
     The print element assembly can be print tested as a stand alone unit. This has many advantages. First, if there is a failure and the unit is discarded, only the cost of the print element is lost, not the entire cost of the print cartridge. Second, after the print test, only the print element is required to be cleaned. The additional wetted area of the port manifold is not inked and therefore does not require cleaning. The fine filter ports also provide a convenient location for the print tester to connect to. 
     The present invention allows for a print cartridge design that is flexible enough to have either an onboard reservoir, a replaceable ink tank, or an external supply would have a high degree of reuse potential and synergy with a number of different products. An additional variation could allow for a head that has an integral ink supply to alternately accept an external ink supply. 
     The ultimate engineering feat would be to design a part that works in many applications. The proposal outlined here is to have a basic print element unit that can accept permanent ink tanks, removable ink tanks, or an external (perhaps tube fed) supply. The base printhead could be the same across all these product families, using common tooling. 
     The basic housing would incorporate all of the features necessary to attach to the print transducer as well as the required electrical interconnect. The lowest common ink delivery would be incorporated into this part. Through either mold inserts or separate parts, the options for the different feed mechanisms would be incorporated. The datum structures and tooling features would be developed off the base part so that the ink delivery variation would not impact the manufacture of the part. 
     A variation of this implementation, which is independent of it, is to allow for an ink tank supplied with ink to have an off head external supply connected to it. For example, a vent in the ink tank could allow for a feature to have a hose fitting from an external reservoir inserted or connected to it. This would allow customers with large graphics requirements to print large jobs without printhead replacement. 
     It should be understood that the foregoing description is only illustrative of the invention. Various alternatives and modifications can be devised by those skilled in the art without departing from the invention. Accordingly, the present invention is intended to embrace all such alternatives, modifications and variances which fall within the scope of the appended claims.