Note: Descriptions are shown in the official language in which they were submitted.
101520253035CA 02265122 2005-04-26TITLE OF THE INVENTIONAutomatic Meter ReaderFIELD OF THE INVENTIONThis invention relates to automatic meterreaders, particularly automated chart recorders.BACKGROUND OF THE INVENTIONChart recorders sense physical parameters, suchas fluid flow, volumes, pressure and temperature, and areoften used in oil and gas producing, processing, andtransportation facilities. These chart recorders consist ofsensing elements mechanically linked to actuate pens thatmark on a chart. The chart rotates or is otherwise advancedby a chart drive. The pens travel across the chart, markingthe variables on the advancing chart paper.Past attempts to capture the sensed variables atthe chart recorders have included linkage driven linear orrotational displacement elements as for example theproposal found in United States patent no. 4,414,634 issuedNovember 8, 1983. This method requires moving parts such aslinkage connections that are subject to wear. These devicesrequire unique calibrations from those normally performedon the chart recorder.Other attempts have included the use of a cameraand supporting hardware mounted in front of the chart torecord and disseminate the chart values as disclosed inUnited States patent no. 4,837,708 issued June 6, 1989.Size, complexity, cost, potential for tampering or theftand reliability would have hampered the adoption of thismethod.l0l5202530CA 02265122 1999-03-052A chart digitizing systenupioneered by the patentapplicant has been developed using existing pen positiondetermining art, and proprietary software to enable themanual tracing of the chart lines once the chart has beencreated, taken off and placed on the digitizing tablet.SUMMARY OF THE INVENTIONConventional chart recorders suffer disadvantagesin that there is an inherent delay in the getting theThe chartinterpretedinformation from the chart and into the system.typicallyâ has to be completed, taken off,before getting the results. The delay presents challengesand difficulties in optimizing operations needing thedata.The invention differs substantially in that theinvention. allows the pen. positions to be detected. andlogged at the recording or indicating instrument in realtime.There is therefore provided in accordance with anaspect of the invention an automatic meter reader,comprising a meter having a movable arm, the movable armhaving an indicator tip, the indicator tip being movablethrough a range of positions in response to the metersensing a physical parameter, and a digitizer mounted onthe meter, the digitizer having a digitizing gridpositioned adjacent the indicator tip for sensing theposition of the indicator tip.The use of the invention allows the chartrecorder pen positions to be detected and processed as thechart is being created. The digital data can be stored tomemory and communicated to other devices. The informationis then readily available for use through a variety ofcommon interfaces.IO15202530CA 02265122 1999-03-053Equipping the marking devices so their positioncan be detected at the point of contact on the chart orchart backing surface allows a direct correlation betweenthe chart recorded data and. the logged "values withoutspecial calibration efforts on the recorder.This system has the advantage of operating as adual system where the ink on paper chart can be retained asthe pen functions are logged.The system has the further advantage that theposition sensing grid and electronics has no moving partsto wear. The system will be accurate, reliable, be easy toproduce and install.These and other aspects of the invention aredescribed in the detailed description of the invention andclaimed in the claims that follow.BRIEF DESCRIPTION OF THE DRAWINGSThere will now be described preferred embodimentsof the invention, with reference to the drawings, by way ofillustration only and not with the intention of limitingthe scope of the invention, in which like numerals denotelike elements and in which:Fig. 1 is a perspective view of a chart recorderand digitizer according to an embodiment of the invention;Fig. 2 is a front view of a chart recordershowing location of movable arms according to an embodimentof the invention;Fig. 3 is a schematic section through the chartrecorder and digitizer of Fig. 1 showing the principalcomponents of an embodiment of the invention;Fig. 4A is a side view of a set of three movablearms with pens according to the invention;Fig. 4B is a top view of the movable arms of Fig.4A;1015202530CA 02265122 2005-04-264Fig. 4C is a bottom view of the movable arms ofFig. 4A; andFig. 5 is a detail of a pen adaptor according toan embodiment of the invention.DETAILED DESCRIPTION OF PREFERRED EMBODIMENTSFig. 1 shows an automatic meter reader which hastwo main parts, a conventional chart recorder 10 that hasbeen modified to incorporate a digitizer 12.The chart recorder 10 may for example be a DRI-FLO II (tm) chart recorder, or an ITT Barton Model 202A or208A differential pressure recorder, but this invention isnot restricted to the particular chart recorder, and may beused on a variety of chart recorders and other meters thathave a movable arm.As shown in more detail in Figs. 2 and 4A-4C, thechart recorder 10 has three mechanically actuated movablearms 14A-14C which are nmunted on pivot points 25Aâ25Cwithin a housing 15, in which is installed a backing plate24. The backingâ plate 24 is installed in conventionalmanner. Each movable arm 14A-14C terminates in an indicatortip which includes a pen tip 16Aâ16C and pen adaptor 18A-18C respectively. Ink reservoirs 29Aâ29B lying on themovable arms 14Aâ14C respectively in conventional fashionprovide ink through ink capillaries 31A-31C respectively tothe pen tips 16Aâ16C respectively. The chart pen adaptors18Aâ18C are located at the end of each movable arm 14Aâ14Crespectively. The chart pen adaptors 18Aâ18C may be each anelectromagnetic coil 27 as illustrated in Fig. 5, having an16Aâ16C extendrespectively into contact with chart paper 20 duringopen core through which the pen tipsoperation. The electromagnetic coils 27 may be glued,crimped or otherwise fastened to the movable arms 14A-14C.The inner movable arm 14C has an angled pen tip 16C, eg atl0l5202530CA 02265122 1999-03-05545° to the vertical, to allow it to fit with the other pentips 16a, 16B.The chart recorder 10 illustrated senses gas flowthrough a dry gas flow sensing assembly 22 connected via aline 30 1x) a well. In response to gas flow (or otherparameter being sensed) in a line (or other device) beingmonitored, the indicator tips 16Aâ16C move through a rangeof positions, typically an arc, in response to the metersensing the physical parameter. The chart 20 rotates abouta spindle 32 in the meter 10. Each movable arm l4Aâ14Cfollows a different arc across the chart in close proximityto each other.Digitizer 12 is mounted on the meter 10 byfitting the digitizer 12 into an opening 26 in the backingplate 24 of the meter 10. The digitizer 12 has a digitizinggrid 28 positioned adjacent the indicator pen tips 16Aâ16Cfor sensing the position of the indicator pen tips 16Aâ16C.Digitizing grids themselves are well known, and any oftypesalthough the onevarious may be used in the operation of theinvention, selected. may requiremodification to fit into a particular meter. In addition,the digitizing pen typically" used with a conventionaldigitizer is replaced by one or more of the chart penadaptors 18Aâl8C mounted on the movable arm of the meterlO.The digitizing grid 28 may be affixed to thechart backing plate 24 in any of various ways, such as bybeing held by screws. The chart pen adaptors 18Aâl8Ctransmit signals to the digitizing grid 28 in known manner.Conventional digitizing electronics and modifiedconventional programming detects the pen adaptor positionsfrom the meter 10 and converts the pen adaptor positionsinto an electricalsignal representative of the penposition or into a digital format.1015202530CA 02265122 1999-03-056tabletincorporating a grid and controllerâ such as the MutohA cordless, electromagnetic digitizerAmerica Pen System available from Mutoh America Inc. ofPhoenix, Arizona, may be used as the digitizer 12. Thereare numerous digitizers that may be adapted for mounting ona chart recorder in accordance with this invention, such asthe Summasketch (tm) digitizer available from SummagraphicsCorporation of Seymour, Connecticut, or the UDâSeriesgraphic tablet available from Wacom Technology Corporationof Vancouver, Washington. The conventional digitizer 12 isprovided with the pen adaptors 18Aâ18C to fit the movablearms 14Aâ14C and modified shape to fit the backing plate24. The digitizer has built in programming which may besuitably modified to suit the particular application. Forexample, the PSCSM (tm) or PSC6 (tm) pen system controllerproducts of Mutoh America may be used. As contained in theMutoh America chart pen, the signal from the pen adaptors18Aâl8C may be frequency encoded to contain pen switchinformation (pen up or down, as well as side switchstates). The digitizer 12 may incorporate a conventionalRS-232 communications port or conventional removable memorycard slot 34. Other data interface devices may be used,transceiver for remotedigitizer 12. Theincluding a reading andinterrogation of the digitizer 12acquires data by sensing the position of the pen adaptors18Aâl8C on the meter 10.The digitizer 12 has particular application tocircular chart recorders used to determine fluid flow. Asshown in Fig. 1, the chart backing plate 24 is replaced ormodified to include an opening 26 to contain the digitizinggrid 28 which may be etched on to a printed circuit boardor screened on a Mylar (tm) grid or other device. In theMutoh America digitizer, the amplitude and frequency of thereceived signal on individual sensor grid lines contain thel0l5202530CA 02265122 1999-03-057information required. to determine pen location, switchstatus and pen pressure. The system may be retrofitted toexisting recorders or enhance newly produced or rebuiltchart recorders with the ability to log the data as it iscreated. The device can also be applied to indicatinginstruments and chart recorders of the strip chart or drumvarietyâ and. digitize the pen jpositions for anyâ of thevariables indicated or recorded. There should be no metalbetween the pen adaptors l8Aâl8C and digitizing grid 28 ifan electromagnetic coil is used as the pen adaptor l8Aâl8C.The pen adaptors 18A-18C may be passive or active(powered). If the pen adaptors l8Aâl8C are powered then thepower is supplied in the conventional manner from thedigitizer 12 along wires that are themselves conventionalbut are adapted for this invention by running the wiresalong the movable arms 14Aâ14C. In some applications, onlya single movable arm 14A, with single pen adaptor 18A andpen. tip 16A. is required. The invention. may" be readilyadapted to any number of movable arms.The digitizer 12 is programmed to sense the penor indicator positions on the meter 10 and process thosesignals into time stamped, digital data that can be storedand made available to other devices through the interface34. The meterâ 10 may also be an instrument that justindicates rather then record (such as pressure gages,speedometers, etc.) In this instance, the indicator tip isa nonâmarking indicator. The digitizer 12 includesconventional digitizer features such as memory for datastorage and power circuitry for low power operation with anexternal battery pack.Resolution of the position of the pen may bechosen to suit the application, but may for example be 1016points per inch, with 0.01 inch accuracy in the verticalposition of the pen or 0.02 inch in the 45 degree position.10CA 02265122 1999-03-058The digitizer 12, when used with more than onepen indicator, may poll the pen indicator positions one penat a time, each uniquely identified as separate pens. Byreading two pens in a gas recorder, wherein bothdifferential pressure and static pressure were measured,would. be enough. to allow calculation. of the gas flow,provided the temperature was manually input or otherwiseentered into downstream gas volume calculation software.A.person skilled in the art could make immaterialmodifications to the invention described in this patentdocument without departing from the essence of theinvention that is intended to be covered by the scope ofthe claims that follow.
