Abstract:
A capacitive sensor for measuring pressure comprises a fixed charge plate integral to a printed circuit board, a flexible charge plate that is grounded, a conductive donut-shaped adhesive spacer between the charge plates, a lid, a non-conductive donut-shaped adhesive spacer between the second charge plate and the lid, means of providing a pressure, fixed or variable, to both sides of the flexible charge plate, wherein a microcontroller controls a power supply and provides a voltage to the first charge plate wherein the accumulative voltage may be measured as a means of determining differential pressure.

Description:
PRIORITY CLAIM 
       [0001]    This application is a divisional of U.S. patent application Ser. No. 11/655,762, entitled “Capacitive Sensor,” filed Jan. 19, 2007, the disclosure of which is incorporated herein in its entirety by this reference. 
       CROSS REFERENCE TO RELATED APPLICATION 
       [0002]    U.S. Pat. No. 6,220,244, “Conserving device for use in oxygen delivery and therapy”, McLaughlin, is herein incorporated in its entirety by reference. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0003]    Not applicable. 
       REFERENCE TO SEQUENCE LISTING, A TABLE, OR A COMPUTER PROGRAM LISTING COMPACT DISC APPENDIX 
       [0004]    Not applicable. 
       BACKGROUND OF THE INVENTION 
       [0005]    Refer to U.S. Pat. No. 6,220,224, “Conserving device for use in oxygen delivery and therapy”, McLaughlin. 
       BRIEF SUMMARY OF THE INVENTION 
       [0006]    None included. 
     
    
     
       BRIEF DESCRIPTION OF THE (INFORMAL) DRAWINGS 
         [0007]    To further clarify the above and other advantages and features of the present invention, a more particular description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. It is appreciated that these drawings depict only illustrated embodiments of the invention and are therefore not to be considered limiting of its scope. The invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which: 
           [0008]      FIG. 1   a  is a schematic diagram illustrating a circuit for driving a single capacitor sensor. 
           [0009]      FIG. 1   b  is a schematic diagram illustrating a circuit for driving a dual capacitor sensor. 
           [0010]      FIG. 2   a  is an exploded side view of a single capacitor sensor. 
           [0011]      FIG. 2   b  is an exploded side view of a dual capacitor sensor. 
           [0012]      FIG. 3   a  is an event timing diagram with a corresponding asymptotic accumulation of voltage across a capacitive sensor and a summation thereof for a given pressure. 
           [0013]      FIG. 3   b  is an event timing diagram with a corresponding asymptotic accumulation of voltage across a capacitive sensor and a summation thereof for variable pressures. 
           [0014]      FIG. 4  is an exploded view of selected components of a single capacitor sensor. 
           [0015]      FIG. 5   a  is an event timing diagram of a waveform of 2 respiratory cycles with a bolus of oxygen delivered during the second inspiration event. 
           [0016]      FIG. 5   b  is time-voltage curve of a single respiratory cycle derived from the amplitudes calculated from multiple measurement cycles. 
           [0017]      FIG. 6  is a schematic of an application of the invention in an electronic oxygen delivery system. 
           [0018]      FIG. 7  depicts time-voltage curves for a single measurement cycle representative of various points in a respiratory cycle. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0019]      FIG. 2   a  depicts a preferred embodiment of the subject invention—a sensor assembly  210  including a single capacitor with at least one sensing plate. Sensor assembly  210  is preferably used as the sensing component of a pressure transducer. Pressure transducers have many applications which are well known in the art and related arts. 
         [0020]      FIG. 2   a  specifically is an exploded, in part, side view of a single capacitive, or capacitor, sensor assembly  210  the invention may include the following fixedly stacked components: a plastic lid  201 ; a first adhesive spacer  202 ; a metalized membrane  203 ; a conductive adhesive spacer  204 ; a copper grounding contact  205 ; a PCB  206 ; a copper shielding plate  207 ; a copper sensing plate  208 ; and a non-conductive mask  209 . 
         [0021]      FIG. 4  is an exploded perspective view of plastic lid  201 ; adhesive spacer  202 , metalized membrane  203 , and adhesive spacer  204  and includes the preferred location of ports  701   a  and  701   b  in plastic lid  201  when the subject invention is used with an oxygen delivery system for general aviation. Ports  701   a  and  701   b  are the ports of the corresponding apertures through lid  201  which enable the introduction of a first pressure, ambient or other, into chamber  219   a  and thereby to top side of the metalized membrane  203  when the stacked components are assembled. In this application of the invention the ports are preferably tubularly coupled with ambient pressure and are approximately 0.125 inches in diameter. 
         [0022]      FIGS. 2   a  and  2   b  do not depict apertures  701   a  or  701   b  nor do they depict means to introduce a second pressure to the bottom side of the metalized membrane  203 —see chamber  219   b . Aligned aperture through non-conductive mask  209 , copper sensing plate  208 , printed circuit board  206 , and copper shielding plate  207  enable the introduction of a second pressure to the bottom side of the metalized membrane  203  via chamber  219   b . In this application of the invention the port defined by these aligned apertures in copper shielding plate  207  (again, not shown) is pneumatically coupled with a cannula or face mask. Apertures are sized and placed so as to evenly and timely introduce pressure changes to chambers  219   a  and  219   b  and thereby metalized membranes  203  and  252  (see chambers  279   a  and  279   b ) and prevent damage to metalized membranes  203  and  252  in the event that the pressure, in either chamber ( 219   a  or  219   b ), is so great, or the opposite chamber ( 219   b  or  219   a ) negative pressure is so great, so as to deflect the membrane  203  or  252  into at least one aperture to damage it sufficiently to effect performance—e.g., plastic deformation. 
         [0023]    The single capacitor sensor  210  in  FIG. 2   a  is preferably used when accurate, precise, and timely pressure measurements are needed when the metalized membrane  203  deflects toward sensing plate  208 . Dual capacitor sensor  250  as depicted in  FIG. 2   b  would be a preferred alternative embodiment when accuracy, precision, and timeliness are needed when metalized membrane  203 , or in  FIG. 2   b  metalized membrane  252  deflects up or down—a true differential pressure sensor. One means of grounding the components in  FIG. 2   b  is depicted. 
         [0024]    Regarding the assembly of the single capacitor depicted in  FIG. 2   a , the first adhesive spacer  202  is a means for securely fixing the plastic lid  201  to metalized membrane  203  wherein the spacer  202  is preferably square with a round aperture and the first chamber  219   a  is defined therein. Preferably first adhesive spacer  202  is substantially non-conductive. Preferably the first chamber  219   a  is substantially sealed so the pressure therein may be controlled and accurately measured. The pressure may be a vacuum or preferably (and as described herein) the lid may have an aperture or port, or more than one, which may introduce a pressure—the pressure source may be regulated or controlled, or alternatively may be an unknown and uncontrolled. In the preferred application of the preferred embodiment of the invention two lid ports  701   a  and  701   b  are coupled to ambient pressure as part of a supplemental oxygen conserving delivery system for use in general aviation. The spacer  202  is preferably substantially non-conductive so as not to affect the charge on the membrane  203 . 
         [0025]    Alternatively the lid may be comprised of a second PCB  266 . PCB  266  (or PCB  206 ) may originally include a copper laminate, or copper laminates, which may be etched to form copper sensing plates  268  and  258  (or copper sensing plate  208 ), and provide copper shielding plates  257  and  267  (or  207 ). 
         [0026]    A second copper sensing plate  268  as illustrated in  FIG. 2   b  will enable symmetrical sensing which may be a significant improvement for some true differential pressure sensor applications. And an additional copper shielding plate  267 , which may be integral to the second PCB  266 , will improve the performance of the dual capacitor sensor as preferably depicted in  FIG. 2   b.    
         [0027]    Shielding plates  207 ,  257  and  267  provide electromagnetic shielding so metalized membranes  203  and  252  and copper sensing plates  208  and  258  and  268  respectively are electromagnetically isolated so as to improve the performance of the capacitive sensors. 
         [0028]    Any of a number of alternative insulating, spacing, and securing means well known in the arts could be employed to achieve the function of spacer  202 . Alternative means of defining a chamber  219   a  are may include a concave cavity (chamber) on the underside of lid  201  and alternative means for non-conductively securing the lid  201  to the membrane  203  including any of a number of adhesives well known in the art. Alternatively various manufacturing processes could be employed wherein these components and their functions could be combined into different, fewer or even a single part such as a plastic molded top that included the functions of lid  201  and means to affix to, and insulate from, membrane  203 . 
         [0029]    Preferably, the metalized membrane  203  is comprised of a flexible aluminized Mylar and is approximately 0.010 inches from the surface of the lid and 0.006 inches from non-conductive mask  209 ). This distance permits the lid  201  to act as a stop when the membrane experiences a significant pressure (negative pressure from the first pressure source in chamber  219   a  or positive pressure from a second pressure source in chamber  219   b —see below). The stop prevents the membrane from experiencing excessive excursion which can be damaging, such as plastic deformation or premature fatigue from repeated excessive pressures/loads. 
         [0030]    Conductive adhesive spacer  204  provides a means of grounding the membrane  203  and securing membrane  203  to the printed circuit board  206  and thereby defining chamber  219   b.    
         [0031]    As was the case with adhesive spacer  202  preferably adhesive spacer  204  is square with a round aperture therein, but any adequate aperture in the spacers could be equally functional and while it is preferred the spacers have the same dimensions it is not necessary. Alternative means of grounding the membrane  203  include a separate electrical contact between the membrane  203  and ground which is independent of the other components in  FIG. 2   a  or wherein membrane  203  is grounded to copper grounding contact  205  independent of conductive adhesive spacer  204 . Preferably membrane  203  is grounded via spacer  204  to copper grounding contact  205  (distinct from substantially insulated from copper sensing plate  208 ) on the PCB  206  when assembled (or etched there from). 
         [0032]    The metalized membrane  203  is a first charge plate and the copper sensing plate  208  is a second charge plate of a capacitor. As described herein, printed circuit board  206  and sensing plate  208  preferably have apertures which share an axis such that they are coupled to a second pressure source which is introduced to chamber  219   b.    
         [0033]    Preferably a non-conductive mask  209  may be disposed between the copper sensing plate  208  and the membrane  203  which will keep the metalized membrane  203  from shorting in the event it is deflected so as to come in contact with copper sensing plate  208 . 
         [0034]    An alternative embodiment, which does not conceptually depart from the single capacitor sensor depicted in  FIG. 2   a  and described, preferably and alternatively herein, is depicted in  FIG. 2   b . Preferably this alternative embodiment includes all the components included in  FIG. 2   b  but it can be appreciated that depending upon the application one skilled in the art could select from the additional components and their functions in  FIG. 2   b  vis-avis  FIG. 2   a  and enable a capacitive sensor. For example, the lid  201  in  FIG. 2   a  may be replaced with another sensing plate—namely, copper sensing plate  268  and conductive adhesive spacer  251  but may not require PCB  266  or copper shielding plate  267  or non-conductive mask  269 . 
         [0035]    Alternatively, lid  201  may simply be replaced with printed circuit board  266  if the device needs another board—the PCB  266  could easily provide all the functions as lid  201 . The non-conductive mask  269  and copper shielding  267  are preferred if this alternative is a dual capacitor sensor which requires a second sensing plate to enable the second capacitor—in this case copper sensing plate  268 . The second sensing plate will provide for two capacitors which is preferred if the application is for a symmetrical differential pressure sensor. Obviously, and consistent with the embodiments described herein apertures in the conductive mask  269 , copper sensing plate  268 , copper shielding plate  267  and printed circuit board  266  would be necessary to maintain a port so as to introduce a pressure to chamber  279   a . Introduction of a pressure to chamber  279   b  would be akin to the chambers  219   a  and  219   b  depicted in  FIG. 2   a.    
         [0036]    Capacitive sensors depicted in  FIGS. 2   a  and  2   b  are driven by the circuits depicted in  FIGS. 1   a  and  1   b  respectively.  FIG. 1   a  depicts a simple RC circuit  101  which includes control means preferably a microcontroller  102 —any of a number of adequate off the shelf controllers are well known in the art including Microchip PIC12C672 or PIC16F676. While the circuit can be driven any number of ways, for example the rise or fall times may vary or the voltage may vary, preferably a digital output  102   a  of microcontroller  102  is a pulse of 5 volts  103  (preferably the rise and fall times are 1 microsecond or less), which is applied through resistor  104  of a known value—preferably 1 M ohm. The resistor limits the current of the applied voltage and may vary based upon principles well-known in the electronic arts. An impedance buffer, preferably an operational amplifier  105 , tracks the voltage and applies it to the analog-to-digital converter input  102   b  on the microcontroller  102  wherein the means for measuring the accumulated voltage takes place. The voltage source  103  and resistance  104  are of known values. The accumulated voltage across the capacitor for a given amount of time will therefore represent the distance between the charge plates in the single capacitive sensor  210 . The components are calibrated and the microcontroller is programmed so the value of the capacitor varies with the air pressure placed upon it—thereby rendering a transducer. Preferably, the device is calibrated such that metalized membrane  203  is an initial distance from fixed charge plate (copper sensing plate)  208  when the pressures in chambers  219   a  and  219   b  are equal and deflects based upon the differential pressure in said chambers. So the pressure put upon the flexible charge plate (metalized membrane  203 ) can be calculated (by software or firmware or a functional equivalent preferably in or downloaded to the microcontroller  102 )—from a single pressure source for absolute pressure or two pressure sources for differential pressure. 
         [0037]    As depicted in  FIG. 1   a  and  FIG. 2   a , the preferred embodiment of the invention is not a true differential pressure sensor but a sensor for use in an oxygen delivery system wherein precise, accurate and timely data on exhalation is not necessary for desirable oxygen conservation. Deflection of membrane  203  toward sensing plate  208  preferably occurs during inspiration or inhalation and deflection toward lid  201  occurs during expiration or exhalation. Accurate, precise and timely data enables the timely delivery of a bolus of oxygen. As depicted in  FIG. 6 , the microcontroller output line  602  represents the conditioned signal from the sensor  210  for external use—in this case signaling valve assembly  605  to open valve  608  which enables a bolus of oxygen to be delivered to the user. 
         [0038]    To illustrate a function of the RC circuit  101 , refer to  FIG. 3   a . One measurement cycle starts with raising the voltage at SD_R  301  from zero to a known value—preferably 5 volts. This is followed by measuring the accumulated voltage across the capacitor at three points A/Ds — 1, A/Ds — 2 and A/Ds — 3 ( 302   a - c )—a single measurement cycle. Sigma  305  represents the addition of these three voltages and may be used to approximate the area under curve  303 . Multiple measurements help zero out noise. This is followed with lowering the voltage to zero—see  306   a  and  306   b  for a time period that allows the capacitive sensor  210  to discharge to or near zero. Another measurement cycle cannot begin until sufficient time has elapsed for the capacitor to discharge to near zero. The zero point can be calibrated by the microcontroller  102  to a baseline if fast repetition rates are necessary. In the most preferred embodiment of the subject invention  16  measurement cycles are made and the values summed and conditioned (including averaging to reduce noise and improve the accuracy of the correlation between accumulated voltage and the pressure on metalized membrane  203 ) to create a value that closely approximates the area under the asymptotic curve  303 . Other means of measuring the accumulated voltage may be employed—as long as these values are properly calibrated to represent a distance between the metalized membrane  203  and sensing plate  208  (which is preferably copper) and therefore a pressure. It should be noted that curve  303  may not be asymptotic—depending upon the circuit characteristics and the pulse characteristics the accumulated voltage may be linear or some other shape. 
         [0039]      FIG. 3   b  illustrates a range of rates of accumulated voltage based upon the processes described in  FIG. 3   a —see SD_A2 in  FIG. 3   b . Each curve represents a different pressure put on membrane  203  which will be described in more detail. These values may be compared to other calculated values derived from the accumulated voltage to either determine a differential pressure in a true differential pressure sensor or alternatively if the capacitive sensor  210  is part of an electronic oxygen conserving delivery system (See  FIGS. 5   a ,  5   b  and  6 ) as a means for tracking respiration to determine the optimal bolus of oxygen and the timing thereof. 
         [0040]      FIG. 7  depicts time-voltage curves for a single measurement cycle representative of various points in a respiratory cycle—exhalation  801 , no breathing  802 , a small rate of inhalation  803 , a moderate rate of inhalation  804  and large rate of inhalation  805 . The x axis is time in seconds (note exponent)—accordingly  16  measurement cycles may be made in a fraction of a second. 
         [0041]      FIG. 5   a  is an event timing diagram of a waveform of 2 respiratory cycles with a bolus of oxygen  505  delivered during the second inspiration event. Other embodiments of this application of the subject invention may deliver gases other than oxygen. 
         [0042]      FIG. 5   b  is time-voltage curve of a single respiratory cycle derived from the amplitudes calculated from multiple measurement cycles.  FIG. 5   b  illustrates how the data derived from the accumulated voltage in single capacitor sensor  210  and described in  FIGS. 3   a ,  3   b , and  7  is manipulated to construct the waveform representative of respiration or breathing. The accumulated measurements of voltage in  FIG. 7  and  FIGS. 3   a  and  3   b , measured in seconds (note x axis exponent) are averaged and added to construct the wave form in  FIG. 5   b  wherein  511  represents a state of no breathing,  512  represents the beginning of an inspiration event ( 510   b  trip threshold for breath detection),  513  represents when an inspiration event may be confirmed and a bolus of oxygen (preferably) is delivered, the area below the baseline (for no breathing)  510   a  and above respiration curve  516  estimates the total volume of inspiration,  514  represents expiration and  515  represents no breathing. Baseline  510   a  may represent zero pressure per calibration of the sensor  210 , and may change based upon accumulated data from prior respiration events). It should be appreciated that other means of mathematical manipulation of the data derived from the accumulated voltage across sensor  210 , or alternatively 250, may yield the same results if the system or device is properly calibrated. 
         [0043]    To elaborate, in  FIG. 5   a    501   a - c  indicate zero pressure, that is, no inspiration or expiration which means membrane  203  is neither trending up or down for which it is calibrated.  502   a - b  indicate a negative pressure or inspiration.  503   a - b  indicate positive pressure or expiration.  504  indicates a triggering event wherein the microcontroller opens the valve  608  in the valve assembly  605  for a calculated time interval to provide a bolus  505  to the cannula or face mask.  502   b  (dotted line) indicates the inspiration superimposed by the bolus  505  and  508  indicates the follow-through of that inspiration event. 
         [0044]    The bolus delivered to the inspiration tube  606  may be delivered to a delivery device such as a cannula or face mask. The bolus will vary depending upon the physical characteristics of the delivery device used by the patient or pilot. It should be appreciated that while the subject invention has been described for use in an oxygen delivery system there are many other applications, non-medical and medical for which it could be utilized. In particular the subject invention could be utilized in a respiratory monitoring system to detect, measure, and report respiratory characteristics based on calculated differential air pressures put upon sensor  210  or alternatively 250. 
         [0045]      FIG. 1   b  depicts two simple RC circuits which drive the dual capacitor sensor  250 . Microcontroller  112  serves the same functions as microcontroller  102  but drives an additional circuit, see digital outputs  112   b  and  112   c  and processes additional data, see analog inputs  112   a  and  112   d . Other devices are depicted in  FIG. 1   b  which may enhance the performance of the device such as barometer  117 , which may be used to determine when a pilot may need supplemental oxygen among other uses. It is well known in the art of aviation that barometers are used to measure pressure altitude. Temperature sensor  118  may also provide data on ambient temperatures which may be useful in optimizing the performance of the device. The interface transceiver  119 , LCD  120 , keypad  121 , and alert device  123  may facilitate the use and enhance the performance of the device. The memory device  112  may store respiration and system data to provide a record for later retrieval which may be used to monitor system performance. 
         [0046]    Regarding microcontroller  112  (or  102 ) any of a number of adequate off the shelf controllers are well known in the art would suffice including Microchip PIC12C672 or PIC16F676. While the circuits depicted in  FIGS. 1   a  and  1   b  may be driven any number of ways that are well known to those skilled in the art, the preferable means of driving the circuits in the dual capacitor sensor  250 , see digital outputs  112   c  and  112   b , is a 5 volt pulse  113   a  and  113   b  respectively, which is alternately applied through resistors  114   a  and  114   b  respectively, which are of a known value—preferably 1 M ohm. The resistor limits the current of the applied voltage and may vary based upon principles well-known in the electronic arts. Impedance buffers, preferably an operational amplifier  115   a  and  115   b , tracks the voltage and applies it to the analog-to-digital converter inputs  112   a  and  112   d  on the microcontroller  112  wherein the means for measuring the accumulated voltages takes place. The voltage sources and resistances are of known values. The accumulated voltage across the capacitor for a given amount of time will therefore represent the position of metalized membrane  252  in dual capacitive sensor  250 . The components are calibrated so the value of the capacitor varies with the net air pressure (see chambers  279   a  and  279   b ) placed upon metalized membrane  252 , so the pressure put thereon can be calculated (by software or firmware or a functional equivalent preferably in or downloaded to the microcontroller  112 )—the accuracy and precision of the dual capacitor sensor  250  is preferably symmetric. 
         [0047]      FIG. 6  is a schematic of an oxygen delivery system  601  which conserves oxygen—an implementation of the subject invention. The inspiration sensor  210  resides on the PCB  206 . The microcontroller  102  controls the power source  603  to provide a voltage  103  to a charge plate (either the flexible metalized membrane  203  or the fixed copper sensing plate  208  but preferably the sensing plate  208 ) in inspiration sensor  210 . When an inspiration event is detected the microcontroller  102  sends an output signal  604  to the valve assembly  605  which opens valve  608  and a bolus  505  is delivered to inspiration tube  606 . The power source  603  may simply be at least one off the shelf battery for a lightweight and/or portable oxygen delivery systems preferably operating at 4.2 volts. Alternatively, the power source may be external to the oxygen delivery system such as the typical 12 volt power available in general aviation aircraft. An adapter may be internal or external to the oxygen delivery system. 
         [0048]    For an oxygen delivery system, or a respiratory monitoring system, preferably the first pressure source introduced to chamber  219   a  is ambient air and the second pressure source introduced to chamber  219   b  by the user via a respiratory tube  606 . 
         [0049]    The metalized membrane  203  or  252  is preferably a metalized Mylar. Due its properties it may be heated to predictably or controllably shrink, which increases the tension in the membrane, which controls the calibration point and may provide a robust and reliable sensor that is easy to make and easy to calibrate and which provides precise measurements in the capacitor  210 . 
         [0050]    An earlier version of the oxygen delivery system  601  is described in detail in the referenced U.S. Pat. No. 6,220,244 issued to the applicant. Many of the embodiments therein can be implemented into the subject oxygen delivery system including: a plurality of status indicators both visual and audio; power conservation methods and devices; means of measuring altitude to improve sensor performance and oxygen delivery performance—including changing the bolus; compilation of sensor data to more accurately detect the optimal time to deliver the bolus and duration of the bolus; and means of rejecting spurious data. 
         [0051]    In regards to the means of detecting barometric pressure to detect changes in altitude, the barometric sensing device  107  or  117  may provide an input signal to the microcontroller when a sufficient change is altitude warrants a modification in oxygen delivery to the pilot or patient or indicates that supplemental oxygen must be used per laws and/or regulations. 
         [0052]    While the &#39;244 patent had a start drive line and sustain drive line in recognition that the solenoid valve in the valve assembly needed less power to be held open than to initially open, the subject invention saves power by going into pulse width modulation to not only use the least power possible to sustain an open valve but to change the duty cycle depending upon the power available—for example the battery voltage. This provides improved energy conservations. 
         [0053]    The disclosed invention has been set forth in the forms of its preferred and alternative embodiments, and described for use in specific applications, but numerous modifications, which do not require independent invention, may be made to the disclosed devices, systems and methods without departing from inventive concepts embodied in the single capacitor sensor  210  which is disclosed and/or claimed herein. 
         [0054]    Specifically, while an application of the subject invention discloses use in an oxygen conserving delivery system and certain embodiments have been directed to a system for pilots it should be assumed aspects of the subject invention and the embodiments thereof are equally applicable to general medicine wherein patients are in need of supplemental oxygen or medical treatment requires careful, accurate and timely respiratory monitoring. Moreover, the improved capacitive sensor may have myriad applications outside of general aviation or medicine. 
         [0055]    The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.