CA1038058A - Optical system for automatic meter reader - Google Patents
Optical system for automatic meter readerInfo
- Publication number
- CA1038058A CA1038058A CA197,955A CA197955A CA1038058A CA 1038058 A CA1038058 A CA 1038058A CA 197955 A CA197955 A CA 197955A CA 1038058 A CA1038058 A CA 1038058A
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- optical system
- optics
- set forth
- axis
- collimating
- Prior art date
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Abstract
ABSTRACT OF THE DISCLOSURE
An optical system consists of a single light source, collimating option, collecting optics and a detector. The system sequentially scans coded, apertured discs to produce a pulse code indicative of the rotational position of the discs.
An optical system consists of a single light source, collimating option, collecting optics and a detector. The system sequentially scans coded, apertured discs to produce a pulse code indicative of the rotational position of the discs.
Description
~38~5~ 5987 OPTICAL SYSTEM FOR AUTOMATIC METER READER
.
This invention.relates to automatic or remote ~éter readers and, in particular, to an optical system for.reading out meters containing coded, apertured discs.
In the power distribution and. measuri~g art, 5- there i9 a need fo~ a remotely readable meter. In a given , l ~: res:idential district, ~or exampLe, each house may have a .. . ., . , . . . . . . i :i . . méter for monitoring electriclty~ ga~, and water consump~
; tion, none o~ which m~y be owned by the same corporate .: entity. M~ltiplying that by the num6er o residences in .
.. the district, it bec~mes apparent that visually reading .. every meter adds substantially; to the overhead of the ~. ,.,: . .. , - . . , ; - . ~ ut~i ty supplying the particular service.
~onsider~ng as a specific example tke electrical .
- power industry and the familiar watt-hour meter, a number I . 15 . of mechanisms have been proposed for remotely reading e~ectrical power consumption, For example, apertured ~ . . . . . .
. discs having a plurality of light sources and a plurality . . o~ detectors ~or reading out the.rotationaL position o~
each disc has been proposed. Alternatively, it has been .s~ggested that dLgital pulses proportional to power consumed be generated and locally counted. Then, upon suitabl~ command, the count is transmitted to a central .
' ' ' 1038~
station, typically by telephone link.
A difficulty with both of these proposals is cost. A further difficulty with the first proposal is the care required in assembling or positioning the optical elements. A urther d.ifficulty with the second proposal is that the information cannot be checked visually, i.e.
the system is not fail-safe, wherein fail-safe does not . mean the power is shut off, rather that the information ~the meter reading) is lost.
As guidelines, the power companies ha~e suggested that the remote reader have low cost, low maintenance, and be :Eail sa:Ee. In addition, it is desirable that the unit be no bulkier than present devices.
In Canadian patent 1,012,609 issued June 21, 1977 and assigned to the assignee of the present invention, a fail-safe remote meter reading system is disclosed. The remote meter reading system has a unique coded disc arrange-ment for encoding the meter reading of a watt-hour meter.
The aperture disc arrangement described therein occupies very little additional space. Accordingly, it is desirable that the reading optics be comparably compact.
In view of the foregoing, it is therefore an object of the present invention to provide an optical system for reading out a plurality of aperture discs.
~ . ~' ' ' !
. ' . ~
~ ~0380$~3 . RD-5987 Another object of the present invention is to . provide a compact optical system for use in reading a :' multit'ude o~ ~hat position indicatorY in a si.ngle'system.
'. ' ' . . . A further object of the present invention is to 5 . provide a low co~t opticaL system for reading apertured . discs'po~ltions' in a use meter.' , :, . . ...................................... . .
.. ' . ' 'Another object of the present invention i9 to ;' ' ' provide an'opt.ical ay9tem ~or a remote reader 9ystem .
, . . . . . . . . .
. ' , , . using', ap~rt,ure discs. ' , ' . A fu~ther ob~ect o~ the present invention is to ,, . , , .. , . :
' .. ' provide a high assembly tolerance optical system for ... . . ..
~ . auto~atic meter .readers. . .' I: ' ' The foregoing objects are achie~ed in the :. . . .
present'invention wherein there is provided a single I5 . . light source, comprising an incandescent lamp, collimating -opties9 comprisi~g a parabolic reflector, scanned aperture . ' discs, collecting optics,'co~prising a pair of reflectors form;ng a folded path optical system, and a photodetect'or.
. ' . A'more complete.understanding of the present . . invention can be obtained by considering the following . . ' detailed description in conjunction with the àccompanying . drawings, in which: ' .
.FIGURE 1 illustrates a preferred embodiment o~
. the optical system in accordance with the present inven-! 3 ,. .
~",3 . ' .
~.,,`. ! , ; . . RD-5987 tion. 1 0~ ~ 0 5 8 FIGURE 2 illustrates in perspective a full . readout system, including the optical system of the .
present lnvention .
.. .. , . . .
. .A~ illustrated ln FIGURE.l, optical system 10 .. . . ..
:. . . comprises a light source 11 and collimating optics 12 ; . .orméd by an annular solid L3 having a parabolic surace : 14 formed thereon. Parabolic surace L4 i8 sUitAb ly .. . , , , . ~
. . .sil~er or aluminum coated to pro~ide ~he necessary LO re1ectance. . . . ~ :
' ' . ' ' , ' ' ' . , .
:` . .Optlcal system 10 further comprises collecting ' . , optics LS formed by a solid 16 having first and second . ~e~lscting sur~ace 17 and 18. Surface 17 is preferably .
: a parabolic reflector and is also suitably silver or . . .
aluminum coated. Surface 18 is preferably hyperbolic .
- and.serves to ~ocus the image of ligh~ source 11 onto . - , ; . photodetector l9,-which preferably contains a.semiconduc-. tor photocell 21~ Reflec~ing surfaces 17 and 18 form a .
. .folded optical path for the light image from light source 11. The combLnation o a parabolic and hyperbolic reflector form what is known in the art as Cassegra~nian optics. Other combinations of primary and secondary . reflecting surfaces may be utilized, as for example, . Dall-Kirkham optics, in which semi-elliptical and , spherical surfaces are utilized as the primary and secondary reflectors, or Newtonian optics, using a parabolic reflector and a flat reflector.
Interposed between collimating optics 12 and collecting opkics 15 is a plurality of masks or plates containing apertures. 'rhese plates, comprising code discs such as disc 22, a scanning disc 23, and a fixed aperture mask 24 provide the encoding of the rotational position of the indici,a on the meter. The encoding o:E -the rotational position of the indicia on the meter is more fully described in the abo~e-identiEied Canad.ian p~tent 1,012,609.
Briefl~, each code plate contains a plurality of arcuate apertures that are sequentially scanned by scanning disc 23, Fixed plate 2~ contains a plurality of slits, one for each of code plates 22. In order for light to pass through plates 22, 23 and 24, it is necessary that the apertures therein be aligned so that the light may pass from collimating optics 12 to collecting optics 15. The slits in fixed plate 24 serve to ensure that only one of discs 22 is read at a time. The positioning of the slits in disc 22 provides a coded output signal as it is scanned by the apertures in scanning disc 23. As scanning disc 23 - `
!--; ' .
~3805~ RD~5987 eraverses the arc containing each of code. discs 22, a plurality of shaft position signals are ob~ained seriatum , ' as the light from source 11 is interrupted or passed to ' , collecting optics 15 and thence to photodetector"l9.
. . .. . .
' '"5 ' '~ There is thus provided a compact optical system , for reading out a plurality of coded discs to provide an ,.' ''electrical signal indicative of the rotational position , ' o a plurality'o~ shat~ by way o~ a,single optical ! ~, ' ' gy9tem having a single light source and a single photo-.
,10 ,, . d'etector. The optical system i~ stationary and securely fixed in place, yet a plurality of code disc~ can ~'e ' ' ,, scanned, depending' upon'the dlameter of the code discs ,' " as compared to the diameter of the scanning disc.
' , ,Light source 11 preferably comprises a filament .
-' 15 , or incandescent type lamp having a reiatively large filament. For exampie, a General Electric type #3026 , lamp operating at a power dissipation of 3 watts has been found suitable. The light output from this lamp is far ~n excess of that required to read'the discs. The large ~ilament is utilized to obtain a large lmage on the ,............ detector side of the optics. In so doing, alignment ' tolerances are greatly increased (loosened) so tha~ the optical syste~ may be readily assembled on a mass produc-tion basis. ' t~ . , , -`\
As previously noted, reflector elements 12 and 15 are formed from a clear plastic, such as acrylic, (methyl methacrylate) or Lexan polycarbonate, having .
. suitably silver or aluminum coated surfaces to provide .
:: 5 the necessary reflection. The curvature of the reflecting .
- ;~ur$aces is provided by casting or pressing the plastia . . .to the desired shspe and then coating the reflecting sur-i . . . faces.
. . ', ,' De~ector lg mAy comprise any sui~able photo-. detector. It i8 préferred howe~er.that the.photosensltive ~ . area of the detector.be relatively.small so as to provide ¦~a hlgh sensitivity, low noise detector... One commercially ¦ ~ avaLlable detector ~ound suitable for the present invention a type 2N5777-80 photocell, also manufactured by the General Electric Company. This particular photocell has ~`'` , - , .an active area of about 0.015 inches square. In theory, .
I any photocell may be utilized. In practice, an active : element whose diameter is less than 0.10 inch is preferred.
The combination o~ large filament light source and small 1 20 detector enables a wide assembly tolerance while maintain-.
. ing a high Qensitivity, lo.w noise detection system ~or . producing an error ree output signal.
The overall operation of the present invention in I combination with a plurality of coded discs may best be .
1~3~0S8 RD-5987 understood by considering FIGURE 2 in which a watt-hour . .
me~er is illustrated having a plurality of coded discs 22a-e attached one each to the shafts connected to a . , ' plurality of indicia used in obtaining' a visual meter .'.:. '' . . . . !
, 5 ' .. reading. As previously noted 9 scanning disc 23, in ;, . ., ;
:. . ' combination with the slits'in fixed plate 24, scans each ' , of codéd discs 22 individually and'provides a series of ,,...' , . . ..o~put. pul~es proportional to. the rotational position oE
.. . . . . .
, .' ' .each of ~he lndicia ad~acent Eront plate 25. Scanning ', ,,10 dise 23 may be turned by any su'itable mechanism such a~
.
' .,, ~ynchronous motor 26. The optical system of the present ., , . ' . , lnven.tion has a diameter equal to or slightly greater than 't~e working diameter of scanning disc,23, i.e. the diameter , . , to t~e outermost,aper~ure. ' '.
I5. . , ' In opera~ion, in response to a signal ~rom the .centra~,station, light source 11 is turned on and synchro-;, nou~.motor 26 is activated. Starting from a rest position .. . .
,!, , ' , scanning disc ~3 sequentially scans the coded discs , '. atta,ched to each of the indicia adjacent plate 25. .Scanning disc 23 i9 turned at a suitable rate, for example one -- .
; . revolut,ion per second, to. provide a beam path interruption rate well within the response time of photodetector 19, . yet not so long as to unduly prolong the reading operation.
I' .
~;? ' ' .
' ~o~380s8 RD-5987 If telephone transmission lines are used as the link betweén the remote meter reader and the central station, it is most likely that the meters would be read at ~ight when the telephone lines are relatively unused, 5; as for example from 12 midnight to 6 a.m. Assuming a rçading time of 1 ~econd per meter, then 21,600 meters can be read Ln the six haur inter~al when the telephone ' ,',' ' ' , ' . . . .
lines are rel~tively inactlve. Ob~iousl~, iE the situatloh .. .. .
r~uired it, the ~e~er may be resd at ~n~ ti~e.
- WhiLe not shown in either FIGURE 1 or FIGURE 2, a light shield surrounding the optical system may be provided so as to obviate erroneous readings of outdoor meters during the daytime.
There i~s thus provided by the present invention . 15 an inproved meeer reading optical-system in which a - plurality of coded discs are illuminated by a single light : . - . . . .
source and scannedg in effect, by a ~ingle pho~odetector.
Further~ the optical system of the present invention is compact and readily its wlthin the meter movement and coded diqcs utilized for remote reading. By virtue of the present invention the entire optical system is-stationary ~hile a plurality of rotating coded dlscs are scanned by an additional rotating scanning disc.
In view of the foregoing, it will be apparent , 9 _ .
.
to those of ~kill in the art that various modifica~ions c~n be made w~thin the spirit and scope of t~e present . . .
. . invention. . . `
'.. ,' ,,'''. ' ' ". . .. ' . ' : ..
.. . . .
~",', '' ' . ' - ' ,, - ' '', ' '' - ", ~ " ' ' ' , . .
'' '.'''' :, ,','' '' '.,, ': .', :' '.,' ,' ' ., ',' ' ' ' . ...... , . , . ;,, ' . . . ..
, ; ' ', ,,, .,. ' . .
. . . ..... . . .. . .
'' , ' ' " ,. '''''' ~ '' ' "" " ;'' ~ ' ''"''' ' ' '' , ' " , ' ' ' "
. ,. ,,: . ' . . .
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. '..... ' ' -: . ,,, '' ' ; ' ~, . ' . ' ''' ,"','',, ,', '' . ' . ' ,, ,', , . ,'.' ''' " '' ,'' " " ' "~' . . . '. ' . . ..
.
. . . .
il ' ' ' ' , ' ' ~ ~ 10-' '' ' ' , 1 , .
: I
.
This invention.relates to automatic or remote ~éter readers and, in particular, to an optical system for.reading out meters containing coded, apertured discs.
In the power distribution and. measuri~g art, 5- there i9 a need fo~ a remotely readable meter. In a given , l ~: res:idential district, ~or exampLe, each house may have a .. . ., . , . . . . . . i :i . . méter for monitoring electriclty~ ga~, and water consump~
; tion, none o~ which m~y be owned by the same corporate .: entity. M~ltiplying that by the num6er o residences in .
.. the district, it bec~mes apparent that visually reading .. every meter adds substantially; to the overhead of the ~. ,.,: . .. , - . . , ; - . ~ ut~i ty supplying the particular service.
~onsider~ng as a specific example tke electrical .
- power industry and the familiar watt-hour meter, a number I . 15 . of mechanisms have been proposed for remotely reading e~ectrical power consumption, For example, apertured ~ . . . . . .
. discs having a plurality of light sources and a plurality . . o~ detectors ~or reading out the.rotationaL position o~
each disc has been proposed. Alternatively, it has been .s~ggested that dLgital pulses proportional to power consumed be generated and locally counted. Then, upon suitabl~ command, the count is transmitted to a central .
' ' ' 1038~
station, typically by telephone link.
A difficulty with both of these proposals is cost. A further difficulty with the first proposal is the care required in assembling or positioning the optical elements. A urther d.ifficulty with the second proposal is that the information cannot be checked visually, i.e.
the system is not fail-safe, wherein fail-safe does not . mean the power is shut off, rather that the information ~the meter reading) is lost.
As guidelines, the power companies ha~e suggested that the remote reader have low cost, low maintenance, and be :Eail sa:Ee. In addition, it is desirable that the unit be no bulkier than present devices.
In Canadian patent 1,012,609 issued June 21, 1977 and assigned to the assignee of the present invention, a fail-safe remote meter reading system is disclosed. The remote meter reading system has a unique coded disc arrange-ment for encoding the meter reading of a watt-hour meter.
The aperture disc arrangement described therein occupies very little additional space. Accordingly, it is desirable that the reading optics be comparably compact.
In view of the foregoing, it is therefore an object of the present invention to provide an optical system for reading out a plurality of aperture discs.
~ . ~' ' ' !
. ' . ~
~ ~0380$~3 . RD-5987 Another object of the present invention is to . provide a compact optical system for use in reading a :' multit'ude o~ ~hat position indicatorY in a si.ngle'system.
'. ' ' . . . A further object of the present invention is to 5 . provide a low co~t opticaL system for reading apertured . discs'po~ltions' in a use meter.' , :, . . ...................................... . .
.. ' . ' 'Another object of the present invention i9 to ;' ' ' provide an'opt.ical ay9tem ~or a remote reader 9ystem .
, . . . . . . . . .
. ' , , . using', ap~rt,ure discs. ' , ' . A fu~ther ob~ect o~ the present invention is to ,, . , , .. , . :
' .. ' provide a high assembly tolerance optical system for ... . . ..
~ . auto~atic meter .readers. . .' I: ' ' The foregoing objects are achie~ed in the :. . . .
present'invention wherein there is provided a single I5 . . light source, comprising an incandescent lamp, collimating -opties9 comprisi~g a parabolic reflector, scanned aperture . ' discs, collecting optics,'co~prising a pair of reflectors form;ng a folded path optical system, and a photodetect'or.
. ' . A'more complete.understanding of the present . . invention can be obtained by considering the following . . ' detailed description in conjunction with the àccompanying . drawings, in which: ' .
.FIGURE 1 illustrates a preferred embodiment o~
. the optical system in accordance with the present inven-! 3 ,. .
~",3 . ' .
~.,,`. ! , ; . . RD-5987 tion. 1 0~ ~ 0 5 8 FIGURE 2 illustrates in perspective a full . readout system, including the optical system of the .
present lnvention .
.. .. , . . .
. .A~ illustrated ln FIGURE.l, optical system 10 .. . . ..
:. . . comprises a light source 11 and collimating optics 12 ; . .orméd by an annular solid L3 having a parabolic surace : 14 formed thereon. Parabolic surace L4 i8 sUitAb ly .. . , , , . ~
. . .sil~er or aluminum coated to pro~ide ~he necessary LO re1ectance. . . . ~ :
' ' . ' ' , ' ' ' . , .
:` . .Optlcal system 10 further comprises collecting ' . , optics LS formed by a solid 16 having first and second . ~e~lscting sur~ace 17 and 18. Surface 17 is preferably .
: a parabolic reflector and is also suitably silver or . . .
aluminum coated. Surface 18 is preferably hyperbolic .
- and.serves to ~ocus the image of ligh~ source 11 onto . - , ; . photodetector l9,-which preferably contains a.semiconduc-. tor photocell 21~ Reflec~ing surfaces 17 and 18 form a .
. .folded optical path for the light image from light source 11. The combLnation o a parabolic and hyperbolic reflector form what is known in the art as Cassegra~nian optics. Other combinations of primary and secondary . reflecting surfaces may be utilized, as for example, . Dall-Kirkham optics, in which semi-elliptical and , spherical surfaces are utilized as the primary and secondary reflectors, or Newtonian optics, using a parabolic reflector and a flat reflector.
Interposed between collimating optics 12 and collecting opkics 15 is a plurality of masks or plates containing apertures. 'rhese plates, comprising code discs such as disc 22, a scanning disc 23, and a fixed aperture mask 24 provide the encoding of the rotational position of the indici,a on the meter. The encoding o:E -the rotational position of the indicia on the meter is more fully described in the abo~e-identiEied Canad.ian p~tent 1,012,609.
Briefl~, each code plate contains a plurality of arcuate apertures that are sequentially scanned by scanning disc 23, Fixed plate 2~ contains a plurality of slits, one for each of code plates 22. In order for light to pass through plates 22, 23 and 24, it is necessary that the apertures therein be aligned so that the light may pass from collimating optics 12 to collecting optics 15. The slits in fixed plate 24 serve to ensure that only one of discs 22 is read at a time. The positioning of the slits in disc 22 provides a coded output signal as it is scanned by the apertures in scanning disc 23. As scanning disc 23 - `
!--; ' .
~3805~ RD~5987 eraverses the arc containing each of code. discs 22, a plurality of shaft position signals are ob~ained seriatum , ' as the light from source 11 is interrupted or passed to ' , collecting optics 15 and thence to photodetector"l9.
. . .. . .
' '"5 ' '~ There is thus provided a compact optical system , for reading out a plurality of coded discs to provide an ,.' ''electrical signal indicative of the rotational position , ' o a plurality'o~ shat~ by way o~ a,single optical ! ~, ' ' gy9tem having a single light source and a single photo-.
,10 ,, . d'etector. The optical system i~ stationary and securely fixed in place, yet a plurality of code disc~ can ~'e ' ' ,, scanned, depending' upon'the dlameter of the code discs ,' " as compared to the diameter of the scanning disc.
' , ,Light source 11 preferably comprises a filament .
-' 15 , or incandescent type lamp having a reiatively large filament. For exampie, a General Electric type #3026 , lamp operating at a power dissipation of 3 watts has been found suitable. The light output from this lamp is far ~n excess of that required to read'the discs. The large ~ilament is utilized to obtain a large lmage on the ,............ detector side of the optics. In so doing, alignment ' tolerances are greatly increased (loosened) so tha~ the optical syste~ may be readily assembled on a mass produc-tion basis. ' t~ . , , -`\
As previously noted, reflector elements 12 and 15 are formed from a clear plastic, such as acrylic, (methyl methacrylate) or Lexan polycarbonate, having .
. suitably silver or aluminum coated surfaces to provide .
:: 5 the necessary reflection. The curvature of the reflecting .
- ;~ur$aces is provided by casting or pressing the plastia . . .to the desired shspe and then coating the reflecting sur-i . . . faces.
. . ', ,' De~ector lg mAy comprise any sui~able photo-. detector. It i8 préferred howe~er.that the.photosensltive ~ . area of the detector.be relatively.small so as to provide ¦~a hlgh sensitivity, low noise detector... One commercially ¦ ~ avaLlable detector ~ound suitable for the present invention a type 2N5777-80 photocell, also manufactured by the General Electric Company. This particular photocell has ~`'` , - , .an active area of about 0.015 inches square. In theory, .
I any photocell may be utilized. In practice, an active : element whose diameter is less than 0.10 inch is preferred.
The combination o~ large filament light source and small 1 20 detector enables a wide assembly tolerance while maintain-.
. ing a high Qensitivity, lo.w noise detection system ~or . producing an error ree output signal.
The overall operation of the present invention in I combination with a plurality of coded discs may best be .
1~3~0S8 RD-5987 understood by considering FIGURE 2 in which a watt-hour . .
me~er is illustrated having a plurality of coded discs 22a-e attached one each to the shafts connected to a . , ' plurality of indicia used in obtaining' a visual meter .'.:. '' . . . . !
, 5 ' .. reading. As previously noted 9 scanning disc 23, in ;, . ., ;
:. . ' combination with the slits'in fixed plate 24, scans each ' , of codéd discs 22 individually and'provides a series of ,,...' , . . ..o~put. pul~es proportional to. the rotational position oE
.. . . . . .
, .' ' .each of ~he lndicia ad~acent Eront plate 25. Scanning ', ,,10 dise 23 may be turned by any su'itable mechanism such a~
.
' .,, ~ynchronous motor 26. The optical system of the present ., , . ' . , lnven.tion has a diameter equal to or slightly greater than 't~e working diameter of scanning disc,23, i.e. the diameter , . , to t~e outermost,aper~ure. ' '.
I5. . , ' In opera~ion, in response to a signal ~rom the .centra~,station, light source 11 is turned on and synchro-;, nou~.motor 26 is activated. Starting from a rest position .. . .
,!, , ' , scanning disc ~3 sequentially scans the coded discs , '. atta,ched to each of the indicia adjacent plate 25. .Scanning disc 23 i9 turned at a suitable rate, for example one -- .
; . revolut,ion per second, to. provide a beam path interruption rate well within the response time of photodetector 19, . yet not so long as to unduly prolong the reading operation.
I' .
~;? ' ' .
' ~o~380s8 RD-5987 If telephone transmission lines are used as the link betweén the remote meter reader and the central station, it is most likely that the meters would be read at ~ight when the telephone lines are relatively unused, 5; as for example from 12 midnight to 6 a.m. Assuming a rçading time of 1 ~econd per meter, then 21,600 meters can be read Ln the six haur inter~al when the telephone ' ,',' ' ' , ' . . . .
lines are rel~tively inactlve. Ob~iousl~, iE the situatloh .. .. .
r~uired it, the ~e~er may be resd at ~n~ ti~e.
- WhiLe not shown in either FIGURE 1 or FIGURE 2, a light shield surrounding the optical system may be provided so as to obviate erroneous readings of outdoor meters during the daytime.
There i~s thus provided by the present invention . 15 an inproved meeer reading optical-system in which a - plurality of coded discs are illuminated by a single light : . - . . . .
source and scannedg in effect, by a ~ingle pho~odetector.
Further~ the optical system of the present invention is compact and readily its wlthin the meter movement and coded diqcs utilized for remote reading. By virtue of the present invention the entire optical system is-stationary ~hile a plurality of rotating coded dlscs are scanned by an additional rotating scanning disc.
In view of the foregoing, it will be apparent , 9 _ .
.
to those of ~kill in the art that various modifica~ions c~n be made w~thin the spirit and scope of t~e present . . .
. . invention. . . `
'.. ,' ,,'''. ' ' ". . .. ' . ' : ..
.. . . .
~",', '' ' . ' - ' ,, - ' '', ' '' - ", ~ " ' ' ' , . .
'' '.'''' :, ,','' '' '.,, ': .', :' '.,' ,' ' ., ',' ' ' ' . ...... , . , . ;,, ' . . . ..
, ; ' ', ,,, .,. ' . .
. . . ..... . . .. . .
'' , ' ' " ,. '''''' ~ '' ' "" " ;'' ~ ' ''"''' ' ' '' , ' " , ' ' ' "
. ,. ,,: . ' . . .
t , -, ,.
'' '' ' ' , , . ~" ,' '', ' ' ': ' '. ., .,, i . , . . , , . .' ' ,.
. '..... ' ' -: . ,,, '' ' ; ' ~, . ' . ' ''' ,"','',, ,', '' . ' . ' ,, ,', , . ,'.' ''' " '' ,'' " " ' "~' . . . '. ' . . ..
.
. . . .
il ' ' ' ' , ' ' ~ ~ 10-' '' ' ' , 1 , .
: I
Claims (7)
1. An improved stationary optical system for remote meter readers having a plurality of rotatable aperture discs and a rotatable scanning disc for scanning portions of said aperture discs comprising:
an incandescent light source having a filament for producing divergent light rays;
collimating optics for collimating said divergent light rays and producing a beam of parallel light rays, said beam being directed by said collimating optics through the apertures in said aperture discs;
collecting optics positioned to receive the light beam passing through said apertures from said collimating optics, said collecting optics comprising at least two reflectors for receiving said light beam and directing said light beam along a folded beam path to a focus to form an image of said filament of said incandescent light source; and photodector means positioned at said focus and having an active area for converting the light passing through said apertures into an electrical signal.
an incandescent light source having a filament for producing divergent light rays;
collimating optics for collimating said divergent light rays and producing a beam of parallel light rays, said beam being directed by said collimating optics through the apertures in said aperture discs;
collecting optics positioned to receive the light beam passing through said apertures from said collimating optics, said collecting optics comprising at least two reflectors for receiving said light beam and directing said light beam along a folded beam path to a focus to form an image of said filament of said incandescent light source; and photodector means positioned at said focus and having an active area for converting the light passing through said apertures into an electrical signal.
2. An improved optical system as set forth in claim 1, wherein said image of said filament of said incandescent light source is larger than said active area of said photo-detector means.
3. An improved optical system as set forth in claim 1, wherein said collimating optics comprises a parabolic reflector.
4. An improved optical system as set forth in claim 1, wherein said collecting optics comprises a Cassegrainian reflector.
5. An improved optical system as set forth in claim 1, wherein said collimating optics has an optical axis, said collecting optics has an optical axis, and said optical axis are collinear and form the axis of said optical system, and said photodetector means is positioned on said axis of said optical system.
6. An improved optical system as set forth in claim 1, wherein said scanning disc has an axis of rotation, and the optical axes of said collimating optics and said collecting optics are parallel to and collinear with said axis of rotation of said scanning disc.
7. An improved optical system as set forth in claim 6, wherein said incandescent light source and said focus are located on said optical axes.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA197,955A CA1038058A (en) | 1974-04-22 | 1974-04-22 | Optical system for automatic meter reader |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA197,955A CA1038058A (en) | 1974-04-22 | 1974-04-22 | Optical system for automatic meter reader |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1038058A true CA1038058A (en) | 1978-09-05 |
Family
ID=4099760
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA197,955A Expired CA1038058A (en) | 1974-04-22 | 1974-04-22 | Optical system for automatic meter reader |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1038058A (en) |
-
1974
- 1974-04-22 CA CA197,955A patent/CA1038058A/en not_active Expired
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