Abstract:
An expandable housing generator configured to occupy a small volume in a primed or standby mode, and a larger volume after the commencement of a chemical reaction to generate a gas comprising oxygen. The expandable housing generator may comprise a base housing, a top housing, a first chamber, a second chamber, and a third chamber. The three chambers may separately store components of a catalytic reaction generating the gas. The three chambers may be joined together upon actuation of an activating device. The top housing and at least one of the three chambers may extend along a vertical direction. The extension may accommodate a foam head produced during the reaction. Additionally, the extension may provide a small form factor and consequently better portability and manageability, while also providing sufficient volume to perform the chemical reactions safely and effectively.

Description:
CROSS-REFERENCED APPLICATIONS 
       [0001]    This application relates to, and claims the benefit of the filing date of, co-pending U.S. Provisional Patent Application Ser. No. 60/762,675, (Docket No. ROSS 3388000), entitled EXPANDABLE HOUSING GENERATOR, filed Jan. 27, 2006, the entire contents of which are incorporated herein by reference for all purposes. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to portable oxygen generators and, more particularly, to a portable oxygen generator utilizing a catalytic reaction within an expandable housing. 
         [0004]    2. Description of the Related Art 
         [0005]    In many applications of portable catalytic oxygen generators, the end use may be for increasing the level of emergency preparedness. These oxygen generators may be stored or carried (e.g., by a consumer, worker, or other professional) in the event that an emergency may occur in which a safe source of oxygen is instantly required. In essence, the oxygen generators are maintained on a standby basis, similar to a typical fire extinguisher. In addition, the oxygen is generated on an on-demand basis at the moment of the emergency (e.g., medical or otherwise). As a result, for most of the life of the device, the oxygen generator is in a “primed mode” or “standby mode.” The period of time during actual operation (i.e., meaning the catalytic generation of oxygen, when the chemicals are mixed and the reaction takes place) may be quite negligible in comparison. 
         [0006]    Furthermore, during the chemical reaction that produces the oxygen, there may be foam that develops on the inside of the reaction chamber. This foam may rise during the course of reaction. The so called “foam head” can typically occupy up to 3 times the volume of the base reactants. This foam may be inhibited or reduced by the use of foam breakers, screens, or surfactants. The chemical reactions, the use of foam breakers, the means to deliver the resulting oxygen, and the activation systems, among other information, may be more extensively described in following pending patent applications. These patent applications are all inventions of a sole inventor, Julian Ross, except in certain cases in which Charles Keyes, Jr. is listed as a co-inventor. The entire contents of the patent applications are incorporated herein by reference for all purposes as the “Ross Catalytic Oxygen Patent Applications”:
       1. Ser. No. 10/718,131, entitled “Method &amp; Apparatus for Generating Oxygen,” filed Nov. 20, 2003, (Docket No. ROSS 2864000);   2. Ser. No. 10/856,591, entitled “Apparatus and Delivery of Medically Pure Oxygen,” filed May 28, 2004, (Docket No. ROSS 2934000);   3. Ser. No. 11/045,805, entitled “Method and Apparatus for Controlled Production of a Gas,” filed Jan. 28, 2005, (Docket No. ROSS 3050000);   4. Ser. No. 11/158,993, entitled “Method and Apparatus for Controlled Production of a Gas,” filed Jun. 22, 2005, (Docket No. ROSS 3050001);   5. Ser. No. 11/159,016, entitled “Method and Apparatus for Controlled Production of a Gas,” filed Jun. 22, 2005, (Docket No. ROSS 3050002);   6. Ser. No. 11/158,377, entitled “Method and Apparatus for Controlled Production of a Gas,” filed Jun. 22, 2005, (Docket No. ROSS 3050003);   7. Ser. No. 11/158,362, entitled “Method and Apparatus for Controlled Production of a Gas,” filed Jun. 22, 2005, (Docket No. ROSS 3050004);   8. Ser. No. 11/158,618, entitled “Method and Apparatus for Controlled Production of a Gas,” filed Jun. 22, 2005, (Docket No. ROSS 3050005);   9. Ser. No. 11/158,989, entitled “Method and Apparatus for Controlled Production of a Gas,” filed Jun. 22, 2005, (Docket No. ROSS 3050006);   10. Ser. No. 11/158,696, entitled “Method and Apparatus for Controlled Production of a Gas,” filed Jun. 22, 2005, (Docket No. ROSS 3050007)   11. Ser. No. 11/158,648, entitled “Method and Apparatus for Controlled Production of a Gas,” filed Jun. 22, 2005, (Docket No. ROSS 3050008);   12. Ser. No. 11/159,079, entitled “Method and Apparatus for Controlled Production of a Gas,” filed Jun. 22, 2005, (Docket No. ROSS 3050009);   13. Ser. No. 11/158,763, entitled “Method and Apparatus for Controlled Production of a Gas,” filed Jun. 22, 2005, (Docket No. ROSS 3050010);   14. Ser. No. 11/158,865, entitled “Method and Apparatus for Controlled Production of a Gas,” filed Jun. 22, 2005, (Docket No. ROSS 3050011);   15. Ser. No. 11/158,958, entitled “Method and Apparatus for Controlled Production of a Gas,” filed Jun. 22, 2005, (Docket No. ROSS 3050012);   16. Ser. No. 11/158,867, entitled “Method and Apparatus for Controlled Production of a Gas,” filed Jun. 22, 2005, (Docket No. ROSS 3050013);   17. Ser. No. 11/438,651, entitled “Method and Apparatus for Generating Oxygen,” filed May 22, 2006, (Docket No. ROSS 2864003);   18. Ser. No. 11/558,374, entitled “Method and Apparatus For Delivering Therapeutic Oxygen Treatments,” filed Nov. 9, 2006, (Docket No. ROSS 3353001);   19. Ser. No. 11/560,304, entitled “Method and Apparatus for Delivering Oxygenated Heated Vapor in Skin Care Applications,” filed Nov. 15, 2006, (Docket No. ROSS 3361002);   20. Ser. No. 11/567,196, entitled “Method and Apparatus for Controlled Production of a Gas,” filed Dec. 5, 2006, (Docket No. ROSS 3367001);   21. Ser. No. 60/699,094, entitled “Method and Apparatus for Generating Oxygen,” filed Jul. 14, 2005, (Docket No. ROSS 2864002);   22. Ser. No. 60/735,011, entitled “Oxygen Patch,” filed Nov. 15, 2005, (Docket No. ROSS 3353000);   23. Ser. No. 60/736,786, entitled “Method and Apparatus for Delivering Oxygenated Heated Vapor in Skin Care Applications,” filed Nov. 15, 2005, (Docket No. ROSS 3361000);   24. Ser. No. 60/742,436, entitled “Flexible Reaction Chamber with Frangible Seals and Activation Methods,” filed Dec. 5, 2005, (Docket No. ROSS 3367000);   25. Ser. No. 60/763,121, entitled “Method and Apparatus for Delivering Oxygenated Heated Vapor in Skin Care Applications,” filed Jan. 27, 2006, (Docket No. ROSS 3361001);   26. Ser. No. 11/614,244, entitled “METHOD AND APPARATUS FOR PROVIDING IMPROVED AVAILABILITY OF BREATHABLE AIR IN A CLOSED CIRCUIT,” filed Dec. 21, 2006, (Docket No. ROSS 3380003);   27. Ser. No. 11/623,721, entitled “METHOD AND SYSTEM FOR PORTABLE BREATHING DEVICES,” filed Jan. 16, 2007, (Docket No. ROSS 3380008); and   28. Ser. No. 11/623,727, entitled “METHOD AND APPARATUS FOR PORTABLE SELF CONTAINED RE-BREATHING DEVICES,” filed Jan. 16, 2007, (Docket No. ROSS 3380009).       
 
         [0035]    The use of foam breakers, screens, or surfactants, as described in the Ross Catalytic Oxygen Patent Applications may be effective solutions for inhibiting the growth of the foam generated during the gas producing reactions. However, in certain instances the increase in positive pressure resulting from the reaction may reduce the effectiveness of the particular solution used for foam breaking. Therefore, allowing a sufficient “head space” for the foam to develop may become a highly desirable alternative. This may be especially true in high flow applications where the pressure may build up to significant levels inside of the reaction chamber (i.e., potentially presenting a safety hazard). The creation of an area of “head space” may be a complete solution or a partial solution. In other words, the portable generator may be designed with head space in addition to a foam breaker solution that may involve a barrier foam breaker such as a screen, mesh, or a surfactant. Alternatively, the head space could obviate the need for any additional foam breaker solution. 
         [0036]    However, designing an area for additional head space into the volume of the reaction chamber(s) may equate to a larger overall form factor for the generator, which may be undesirable. It would be beneficial to provide the additional volume when it is required (e.g., during the chemical reaction), but to otherwise maintain the smallest possible form factor for the majority of the life of the device (e.g., such as during storage and transportation). 
       SUMMARY OF THE INVENTION 
       [0037]    An expandable generator for catalytically producing a gas that comprises oxygen. The expandable generator may comprise a housing base and a housing top translatably coupled to the housing base. The housing base may contain a first chamber, a second chamber, and a third chamber. The first chamber, the second chamber, and the third chamber may be separated from one another by frangible seals. The first chamber, the second chamber, and the third chamber may respectively store a first component, a second component, and a third component of a chemical reaction to produce the gas. The expandable generator may further comprise one or more activation tabs configured to breach the one or more frangible seals when actuated, thereby commencing the chemical reaction. The housing top and at least one of a group consisting of the first chamber, the second chamber, and the third chamber, may be configured to extend along a vertical direction. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0038]    For a more complete understanding of the present invention and the advantages thereof, reference is now made to the following Detailed Description taken in conjunction with the accompanying drawings, in which: 
           [0039]      FIG. 1A  shows an embodiment of an oxygen generator according to the present invention in a “standby mode”; 
           [0040]      FIG. 1B  shows the generator of  FIG. 1A  partially deployed; 
           [0041]      FIG. 1C  shows the generator of  FIG. 1A  fully deployed; 
           [0042]      FIG. 2A  shows an embodiment of an inner cartridge prior to activation; 
           [0043]      FIG. 2B  shows the inner cartridge of  FIG. 2A  subsequent to activation and fully expanded; 
           [0044]      FIG. 3A  shows cross-sectional side view of an embodiment of an outer housing and a single inner cartridge assembly in a stand by mode; 
           [0045]      FIG. 3B  shows cross-sectional side view of an embodiment of an outer housing and double inner cartridge assembly in a stand by mode; 
           [0046]      FIG. 4A  shows a cross-sectional side view of another embodiment of an outer housing and double inner cartridge assembly in a stand by mode; and 
           [0047]      FIG. 4B  shows a cross-sectional side view of the outer housing and double inner cartridge assembly of  FIG. 4A  subsequent to activation and fully expanded. 
       
    
    
     DETAILED DESCRIPTION 
       [0048]    In the following discussion, numerous specific details are set forth to provide a thorough understanding of the present invention. However, those skilled in the art will appreciate that the present invention may be practiced without such specific details. In other instances, well-known elements have been illustrated in schematic or block diagram form in order not to obscure the present invention in unnecessary detail. Additionally, for the most part, details concerning well known features and elements have been omitted inasmuch as such details are not considered necessary to obtain a complete understanding of the present invention, and are considered to be within the understanding of persons of ordinary skill in the relevant art. 
         [0049]    The entire contents of Provisional Patent Application Ser. No. 60/762,675, (Docket No. ROSS 3388000), entitled “EXPANDABLE HOUSING GENERATOR”, filed Jan. 27, 2006, is incorporated herein by reference for all purposes. 
         [0050]    Turning now to the drawings,  FIG. 1A  shows an illustrative embodiment of the present invention. In this drawing, reference number  10  generally indicates an expandable oxygen generating device  10 . The expandable generator  10  may comprise an outer housing base  100 , an outer housing top  110 , and a primed volume  125 . The expandable generator  10  may be seen in  FIG. 1A  in a primed mode, in which the outer housing top  110  abuts a top edge of the outer housing base  100 . The primed volume  125  may be sufficient to accommodate the chemical reactants, actuation mechanisms (if any), and filtration apparatus (if any). The outer housing top  110  may be releasably coupled to the outer housing  100  through the use of tabs, clasps, belts, overlapping interconnecting structures, among others. The outer housing top  110  may be vertically movable with respect to the outer housing base  100 . In this illustrative embodiment, the outer housing top  110  and the outer housing base  100  may be made of a rigid plastic or thermoplastic, such as for example polycarbonate or acrylonitrile butadiene styrene (ABS), among others. 
         [0051]    Turning now to  FIG. 1B , the expandable generator  10  is shown at a point in time after the commencement of the oxygen producing catalytic chemical reaction. The outer housing top  110  may be translatably coupled with the outer housing base  100  via a flexible member  120 . The outer housing top  110  may be effectively extended or raised relative to the outer housing base  100 . The outer housing base  100  may remain relatively static or stationary.  FIG. 1B  shows the expandable generator  10  partially deployed. The flexible member  120  may be configured in the form of an accordion, so as to extend and fold as the unit is activated or placed into storage. 
         [0052]    Turning now to  FIG. 1C , the expandable generator  10  may be fully deployed. The outer housing top  110  may be at a maximum height relative to the outer housing base  100 . The flexible member  120  may be fully expanded. In addition to the primed volume  125 , the expandable generator  10  may now comprise a top head volume  135 . Any foam generation that may occur as the result of the oxygen generating reaction may move into the top head volume  135 . 
         [0053]    Turning now to  FIG. 2A , the expandable generator  10  ( FIG. 1A ) may comprise an inner cartridge  200 . The inner cartridge  200  may contain the reaction and provide an activation mechanism. The inner cartridge  200  may comprise a first chamber  210 , a second chamber  220 , and a third chamber  230 . The inner cartridge  200  may also comprise a frangible seal  212 , a frangible seal  214 , activation tags  215 , and activation tags  225 . In addition, the inner cartridge  200  may comprise an outlet port  240 . The outlet port  240  may provide an exit for the generated oxygen or gas, as the case may be, to exit the inner cartridge  200  and be transported to a user via a delivery tube, for example. 
         [0054]    The first chamber  210  may be separated from the second chamber  220  by the frangible seal  212 . The second chamber  220  may be separated from the third chamber  230  by the frangible seal  214 . Each of the three chambers  210 ,  220 ,  230 , may separately contain a component required for the oxygen producing chemical reaction. By manipulating the activation tags  215 ,  225  (e.g., by pulling away from each other), the frangible seals  212 ,  214  may be breached, allowing the chemical reactants to combine and commence the chemical reaction. However, other methods may be used to breach the frangible seals  212 ,  214 , such as applying pressure to one or more of the chambers  210 ,  220 ,  230 , for example. In certain embodiments, the inner cartridge  200  may be made of a flexible material including, but not limited to plastic, rubber, neoprene, among others, and may be configured to expand upon commencement of the reaction. 
         [0055]    Turning now to  FIG. 2B , this drawing shows the inner cartridge  200  in a fully expanded state, after the commencement of the reaction. As seen in this figure, all three chambers  210 ,  220 ,  230  may have expanded beyond their storage or primed configuration. However, embodiments of the present invention may not be limited to this example. In certain embodiments, the three chambers  210 ,  220 ,  230  may only have one expanding chamber, or two or more expanding chambers. As shown in  FIG. 2A , the third chamber  230  may be formed with a series of folds to allow for an increased level of expansion after commencement of the reaction. The outlet port  240  may be configured to be attached to the top of the inner cartridge  200 . In such a case, the outlet port  240  may rise as the inner cartridge  200  expands. Prior to the outlet port  240  may be a foam breaker and/or a foam filter (not shown). The foam breaker may comprise open celled foams, coarsely woven materials, or expanded extrusions, among others. The material for the foam breaker may comprise polypropylene, polyethylene, among other materials inert to the catalytic oxygen generating reaction specifics and not configured to absorb water (i.e., hydrophobic). Various types of materials used in the foam breaker may create an open cell structure that may facilitate the flow through of gas but effectively break down the bubbles of the foam, potentially suppressing the growth of a foam head within the inner cartridge  200 . The foam breaker may also act as a pre-filter, breaking down bubbles, speeding the release of oxygen, and facilitating the return of water to the catalytic reaction. Additionally, the foam breaker may create a tortuous path for the generated oxygen gas, allowing the condensing of water and a cooling of the oxygen gas. More details and alternative embodiments for cartridges and activation of cartridges may be found in the Ross Catalytic Oxygen Patent Applications, the entire contents of which are incorporated herein by reference for all purposes. 
         [0056]    Turning now to  FIG. 3A , the expandable generator  10  may comprise the inner cartridge  200 . As shown in this figure, the expandable generator  10  may be in a primed or standby mode, prior to commencing of the chemical reaction. The outer housing top  110  may be adjacent to the outer housing base  100 . In addition, the outlet port  240  may extend through the outer housing top  110 . As shown in the previous figures, as the inner chamber  200  expands, the outer housing top  110  may extend along with the outlet port  240 . The outer housing base  100  may be adhered or attached to the first chamber  200  to prevent the inner cartridge  200  from moving within the outer housing base  100  or becoming separated from the outer housing base  100 . The inner cartridge  200  may be attached to the outer housing base  100  through the use of brackets (not shown) situated proximate to an interior surface of the outer housing base  100 . Otherwise, the inner cartridge  200  may lift up as the outer housing top  110  is moved in an upward direction relative to the outer housing base  100  after activation. 
         [0057]    Turning now to  FIG. 3B , another illustrative embodiment of the present invention may comprise an expandable generator  30  containing two or more inner cartridges  200  (e.g., two are shown in the figure) in a larger outer housing base  300  and outer housing top  310 . The first chamber  210  of each of the inner cartridges  200  may be attached to outer housing base  300  to prevent their moving up relative to the outer housing base  300  after activation. The inner cartridges  200  may be directly attached to the outer housing base  300  via chemical adhesives, fasteners, among others, or indirectly attached to the outer housing base  300  via intermediary members such as brackets situated at an interior surface of the outer housing base  300 , for example. The inner cartridges  200  may be removably attached to the outer housing base  300  so as to facilitate repair or reuse of the outer housing base  300  and the outer housing top  310  after a single emergency use. The outer housing top  310  may be movably coupled with the outer housing base  300  via a flexible membrane (not shown in this view). 
         [0058]    The two inner cartridges  200  may be fluidly coupled with an outlet manifold  340 . The outlet manifold  340  may be directly attached to each of the inner cartridges  200 . Alternatively, the outlet manifold  340  may be attached to each of the outlet ports  240  ( FIG. 2A ). The outlet manifold  340  may be coupled with the outer housing top  310  and configured to rise along with the outer housing top  310  after activation of the chemical reaction. Although only two inner cartridges  200  may be shown, the outlet manifold  340  may be configured to couple three or more inner cartridges  200  together within an appropriately sized outer housing. 
         [0059]    Turning now to  FIG. 4A , another embodiment of the present invention may comprise an expandable generator  40 . The expandable generator  40  may comprise an outer housing base  400  and an outer housing top  410 . Within the outer housing base  400 , and the outer housing top  410 , the expandable generator  40  may comprise two or more inner cartridges  200 , an outlet manifold  440 , expandable connections  450 A,  450 B, an outlet riser  460 , and a water trap  500 . The water trap  500  and/or the inner cartridges  200  may be secured to the outer housing base  400  via a bracket  510 . 
         [0060]    The outer housing base  400  may further comprise a base lip  402  extending outward from the top edge of the outer housing base  400 . The outer housing top  410  may further comprise a top lip  412  extending toward the interior of the outer housing top  410  from a lower edge of the outer housing top  410 . The base lip  402  and the top lip  412  may substantially overlap one another in a vertical direction when the outer housing top  410  is assembled to the outer housing base  400 . Additionally, an outer edge of the base lip  402  may slidingly abut an interior surface of the outer housing top  410 . An interior edge of the top lip  412  may slidingly abut an exterior surface of the outer housing base  400 . The outer housing top  410  may slidingly translate in a vertical direction relative to the outer housing base  400  after activation of the chemical reaction. Seals  405 A,  405 B,  405 C, and  405 D, may allow the outer housing top  410  to sealingly slide relative to the outer housing base  400  after activation. The slidable coupling between the outer housing top  410  and the outer housing base  400  may eliminate the need for a flexible member attached to both components (e.g., as with flexible member  120  in expandable generator  10  shown in  FIGS. 1B and 1C ). As shown in  FIG. 4A , the outer housing top  410  and the outer housing base  400  may be in a primed or standby mode. 
         [0061]    Two or more inner cartridges  200  may be contained within the outer housing base  400  and the outer housing top  410 . The inner cartridges  200  may be fluidly coupled to one another via the outlet manifold  440 . The outlet manifold  440  may be fluidly coupled via the expandable connection  450 A to an inlet of the water trap  500 . An outlet of the water trap  500  may be fluidly coupled via the expandable connection  450 B to the outlet riser  460 . The outlet riser  460  may be coupled to the outer housing top  410 , so as to rise along with the rising of the outer housing top  410  after commencement of the chemical reaction. 
         [0062]    The water trap  500  and/or the inner cartridges  200  may be secured to an interior surface of the outer housing base  400  through a bracket  510 . Alternatively, the water trap  500  and/or the inner cartridges  200  may be secured to an interior surface of the outer housing base  400  through the use of fasteners, welding (ultrasonic or otherwise), adhesive, straps, or interconnecting surfaces, among others. The securing of the water trap  500  and/or the inner cartridges  200  may inhibit or prevent the unintended movement of these components during shipping and storage and inhibit or prevent the rising up of these components along with the rising of the outer housing top  410  relative to the outer housing base  400  after activation of the chemical reaction. 
         [0063]    Turning now to  FIG. 4B , the expandable generator  40  is shown in a fully expanded state after activation of the oxygen producing chemical reaction. The outer housing top  410  may have translated relative to the outer housing base  400  such that an additional head distance of D1 may be present. Within the outer housing base  400  and the outer housing top  410 , the inner cartridges  200  may also be at a fully expanded state. As the inner cartridges  200  expand, they may move the outlet manifold  440  with respect to water trap  500 . The expandable connection  450 A may expand to accommodate this difference in distance. The expandable connection  450 A may be in the form of a convoluted tube folded upon itself. Alternatively, the expandable connections  450  may comprise a resilient material able to stretch an appropriate distance without folds, or the expandable connection  450  may comprise an extra length of resilient tubing stored within the outer housing base  400 . The outlet riser  460  may comprise some extra tubing to allow the outer housing top  410  to be opened without disconnecting the outlet riser  460 . 
         [0064]    The expandable generator  40  may be used as follows. The expandable generator  40  may be retrieved from storage in a primed or standby mode may be retrieved from storage. The activation tabs  215 ,  225  ( FIG. 2A ) may be pulled or actuated. The frangible seals  212 ,  214  ( FIG. 2A ) may be breached, allowing the previously separated reactants in each of the three chambers  210 ,  220 , and  230 , to flow together, commencing an oxygen producing catalytic reaction. The inner cartridges  200  may start to expand, slidably moving the outer housing top  410  away from the outer housing base  400 . As the inner cartridges  200  expand, the outlet manifold  440  moves away from the water trap  500 . A flexible connection  450 A may provide for the maintaining of the fluid connection between the outlets of the inner cartridges  200  and the inlet of the water trap  500 . As gas flows through the tubing, the gas may be bubbled through water contained within the water trap  500 . Bubbled gas may then exit from the water trap  500 . 
         [0065]    The bubbled gas may flow from the exit of the water trap  500  into an expandable connection  450 B. The expandable connection  450 B may allow the outlet riser  460  to remain coupled to the outer housing top  410  through the expansion. From the outlet riser  460 , the generated oxygen gas may be administrated to a user or victim of an emergency situation. 
       ALTERNATIVE EMBODIMENTS 
       [0066]    The outer housing top may rise relative to the outer housing base due to a pressure build up within an activated inner cylinder. However, the outer housing top may be manually pulled away from the outer housing base. Additionally, or alternatively, a separate mechanism may exists for moving the outer housing top away from the outer housing base, such as a lever, linkage, pneumatic strut, among others. Also, the outer housing top may be held in place away from the outer housing base due to a support mechanism. 
         [0067]    Having thus described embodiments of the present invention by reference to certain exemplary embodiments, it is noted that the embodiments disclosed are illustrative rather than limiting in nature. A wide range of variations, modifications, changes, and substitutions are contemplated in the foregoing disclosure. In some instances, some features of an embodiment of the present invention may be employed without a corresponding use of the other features. Many such variations and modifications may be considered desirable by those skilled in the art based upon a review of the foregoing description of the illustrative embodiments. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the invention.