CA1210109A - Electrical measuring instrument - Google Patents
Electrical measuring instrumentInfo
- Publication number
- CA1210109A CA1210109A CA000402727A CA402727A CA1210109A CA 1210109 A CA1210109 A CA 1210109A CA 000402727 A CA000402727 A CA 000402727A CA 402727 A CA402727 A CA 402727A CA 1210109 A CA1210109 A CA 1210109A
- Authority
- CA
- Canada
- Prior art keywords
- circuit board
- digital display
- dial
- display
- pointer
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Abstract
ELECTRICAL MEASURING INSTRUMENT
Abstract A modular analog/digital display for use in a cylindrical aircraft instrument housing is designed to enable the digital components to be assembled without interference to the analog meter mechanism. The digital display is of the leadless type and is clamped under compression to a circular circuit board with a pair of contact strips in registration with contacts formed on the circuit board and digital display.
The design also features a screw-on dial pointer which facilitates the assembly of the digital display components and dial to the analog meter mechanism without interference. The pointer includes an externally threaded shaft attached at right angles thereto and a locknut threaded over the threaded pointer shaft. An internally threaded bushing is fastened within one end of the hollow meter shaft. An analog dial, having a central opening for accommodating the meter shaft, is slipped over the meter shaft and mounted to the meter mechanism housing or other components. The pointer shaft is then screwed into the bushing, which acts to stiffen the thin-walled shaft, until the pointer is at a desired angular position and distance relative to the dial. The locknut is turned until it is seated on the bushing to secure the pointer at the desired position.
Abstract A modular analog/digital display for use in a cylindrical aircraft instrument housing is designed to enable the digital components to be assembled without interference to the analog meter mechanism. The digital display is of the leadless type and is clamped under compression to a circular circuit board with a pair of contact strips in registration with contacts formed on the circuit board and digital display.
The design also features a screw-on dial pointer which facilitates the assembly of the digital display components and dial to the analog meter mechanism without interference. The pointer includes an externally threaded shaft attached at right angles thereto and a locknut threaded over the threaded pointer shaft. An internally threaded bushing is fastened within one end of the hollow meter shaft. An analog dial, having a central opening for accommodating the meter shaft, is slipped over the meter shaft and mounted to the meter mechanism housing or other components. The pointer shaft is then screwed into the bushing, which acts to stiffen the thin-walled shaft, until the pointer is at a desired angular position and distance relative to the dial. The locknut is turned until it is seated on the bushing to secure the pointer at the desired position.
Description
~ Z 1 ~ ~ O ~ 41.983/1011 ELECTRICAL MEASURING INSTRUMENT
_ _ _ Background of the Invention 1. Cross reference to related applications This application is related to Canadian applications Ser. No. 402,745 entitled "CIRCUIT BOARD MOUNTING ARRANGEMENT
FOR USE IN CYLINDRICAL INSTRUMENT HOUSING", and Ser. No.
402,728 entitled "MODULAR BACKLIGHTE~ ANALOG/DIGITAL INSTRUMENT
DISPLAY", filed simultaneously with the present application, and assigned to the assignee of the present application.
_ _ _ Background of the Invention 1. Cross reference to related applications This application is related to Canadian applications Ser. No. 402,745 entitled "CIRCUIT BOARD MOUNTING ARRANGEMENT
FOR USE IN CYLINDRICAL INSTRUMENT HOUSING", and Ser. No.
402,728 entitled "MODULAR BACKLIGHTE~ ANALOG/DIGITAL INSTRUMENT
DISPLAY", filed simultaneously with the present application, and assigned to the assignee of the present application.
2. Field of the Invention -The invention relates to the field of indicating instruments, and more particularly to a pointer mounting arrangement for use with an analog type electrical measuring instrument.
3. Description of the Prior Art Aircraft and aerospace instruments have traditionally comprised one or more analog meter movements mounted within a housing and coupled to a pointer disposed adjacent an analog dial having graduated markings formed thereon. For convenience in reading such instrumen~s in darkness or under poor conditions of illumination, these instruments are often provided with some form of backlighting or edge-lighting to illuminate the dial and/or pointer.
While such analog instruments have found widespread use throughout the aerospace industry such instruments have a major drawback in that an analog instrument must be interpreted by the ~' - 1 -L21~1~9 ~
!, human observer. Such o~servations are prone to error, especially in view of the literally o~zens of such instruments ~hich must be constæntly scanned in modern cx~erciæl and military aircraft.
In order to obviate these probl~s .here h2s been a demænd for more precise display of critical operatins paraDeters such as ~-can be provided ky digital displays. For hL~æn engineering purposes, it is generally desirable to combine an analog display - -with a digital display of a critical cperating ?arameter. -:
Severe environ~ent~l constraints are placed o~ æny proposed lQ analog/digital instrument d~sign. Such instru~ents must be rugged, accurate and relia~le even when subjected to extremes of temperature, pressure, and vibration as is comncr. in aircraft and aerospace environments. In addition, military and com~ercial standards dictate that most panel instruments be circular in shape and fit within standardized openinSs (diameter and depth) in an r,",,' instrument Fanel. A problem arises in that the large nu~ber of ~
electronic components needed to drive a digital display or used for signal conditioning of an analo~ display will often fill the _-spaoe available behind the mounting panel without leaving sufficient room for the analog (mechanical) movement. The r~",.
complexity c~ ccmponents and lack of space within the instrument ..
housing also make it diffic~lt to assemble the digital display and :
analog meter movement together without interfe ~lce with each other and to readily interoonnect oomponents on adjacent circuit boards. Such difficulties increase manufacturing and repair ~-cost50 In addition, the oamplexity of such displays makes it difficult to a& pt an instrument to different lighting requirements and display types, e.g. light emitting diode (~E~), liquid crystal (LCD), incandescent displays cf the integral lead ~::
or leadless types which are edge-illuminate~, backlighted or ~-unilluminated, for example. ~-A particular pro~le~ associated with assembling the analog~:
display components resides in attaching the pointer to the analog meter shaft. In some instances it is desirable to have the --pointer attached after a~l other cGm æ nents, including the dial, have been mounted to the housing of the an~log meter movement.
This has the advantage that only a single central opening in the -~Zl~9 dial and associated internal components is required to enable these components -to be slipped over the meter shaft and assembled to the meter housing. Thus no radial slots or openings are needed which would detract from the appearance of the dial.
However, several problems arise in attaching a pointer to a meter shaft. The angular position of the pointer with respect to the meter shaft and dial should be readily adjustable.
The distance of the pointer from the front surface of the dial should also be adjustable to allow for slight variations in the thickness of the dial and associated components. In addition, as meter shafts are generally formed from light-weight extremely thin-walled tubing (to reduce weight and inertia) the method of attaching the pointer to the meter shaft should not place any substantial stress on the meter shaft, else the meter shaft may be twisted or otherwise distorted.
There is thus a need for an improved arrangement for mouhting a pointer to an analog meter shaft which places little stress on the meter shaft during assembly and which further enables both the angular position and distance of the pointer relative to the dial to be quickly and easily adjusted.
There is also a need for a compact and modular analog/
digital instrument which is adaptable to various types of displays and lighting techniques and in which the digital display can be assembled or disassembled without interference to the analog meter movement in order to facilitate manufacturing, and to thus reduce assembly and repair costs.
Summary of the Invention .
It is a general object of the present invention to provide an improved electrical measuring instrument.
This and other objects are attained, in accordance with a broad aspect of the invention, by a modular analog/digital instrument display for use in a cylindrical housing including:
a base adapted to fit within said housing; an analog meter movement adapted to fit within said housing and mounted to said base, said meter movement including a rotatable shaft having a portion thereof extending in a direction substantially parallel to the longitudinal axis of said housing; a circuit board adapted to fit within said housing and mounted in aspaced-apart relationship to said meter movement, said circuit board including electrical contacts formed on at least a portion thereof, said circuit board further having an opening formed therein for receiving said meter movement shaft; a digital display; means for mounting said digital display to said circuit board including means for electrically connecting electrical contacts of said digital display with said contracts of said circuit board, an analog dial adapted to fit within said housing and mounted to said circuit board, said dial including a first opening for receiving said meter movement shaft and a second opening for exposing said digital display to view; and a dial pointer mounted to the end of said meter movement shaft extendlng through said dial, said dial pointer being arranged adjacent to a face of said dial.
Brief Description of the Drawing Figures These and other features and advantages of the present invention will be readily understood with reference to the following detailed description of the preferred embodiments of the invention, when taken in conjunction with the accompanying drawing figures wherein;
Fig. 1 is an exploded perspective view of the circuit board mounting arrangement and modular analog/digital instrument displays for use therewith;
.~ 121~ 9 ~- 1 Fig. 2 is an exploded perspective view of another form of circuit bc2rd mounting arrang~ent in accordæ~ oe with the prese~t invention; -Fig. 3 is a partial cross-sectional view of o~e form of circuit board mounting arransement;
Figs. 4 and 5 shcw ~odified versions of the circuit board mounting arrangment of Fig. 2;
Fig. 6 is an exploiei perspective view of one form of backlighted analog/digital instrument display for use with the lQ circuit board mou~ting arrange~ents shown in Figs. 2 through 5; -Fig. 7 shcws one for~ of digital display mounting for use wi~h thR instrument of Fig. 6;
Fig. 8 is a cross-sectional view ta~en along plane 8-8 of Fig. 6; ~
Fig. 9 is an exploded perspective view of an alternative form of backlighted analog~digit~l instrument display wherein the _-digital display is eage-lighted;
Fig. 10 is an explcded perspective view of an analog/digital display showing an alternative form of mounting for the di~ital dis~lay;
Fig. 11 is a detail cross-sectional view taken alons plane A-A of Fig. 15 showing details of construction of a screw-on ~-poin~er; 1-Figs. 12a, b, c respectively show a front plan ~iew, a side ~--cross-sectional view and a rear plan view c~ a typical instrument housing in which the devi oe s of Figs. 1-10 are designed to be mounted; and E
Fig. 13 is a block diagram of circuitry representative of that which can be mounted to the circuit board arrangements of Figs. 2-5 and which is useful with t~e analog/digital instruments ~-of Figs. 6-10.
Detailed D scr~ption of the Preferred Embodiments ~-1. Overall system arrangement 3~ Fig. 1 shcws the overall relationship of the circuit board mounting arrangement, deno~e~ generally at 100, with three tvpes ... .. . . . . .. .. .............................................. --.. -- -- -- - - .. ............................................ ..
Zl~9 of modular analo~/digital instrument display zssemblies, denoted æs 200, 300 and 400. -~ore paLr.icularly analog~digital display zsse~bl~ 200 --includes a self~ uminated digital dis?lay (such æs .hat formed frcm light emitting dio~es or incandesoe nt lam?s) æ~d an --illuminated dial ænd pointer. Display asse~bly 300 features a non-self-illuminated display ~such as a liquid crystal display) and means for edge-lighting this display ænd backlighting an analog dial and pointer. Display æsse~bly 400 features a 1~ scre~on-pointer and shcws an technique for mounting a leadless digital display to a circuit board for use with æn ænaloq/digital instru~ent assembly. -:
As will be described in more detail belc~, the circuit board mounting arrangement 100 and modular display arrangements 200, 300 t and 400 enable a ccmp~ct and rugged 2n210g/digital aircr2ft or aerospace instrument to b~ constructed which is designed to fit within t~e confines of a small diameter (e.g. 2 inch) cylindrical instrument housing, such as is shc~n in Figs. 12a - c.
Each of the above mentioned assemblies will ncw ~e described L--in more detail.
2. Circuit board n~ounting arrangment With reference to Figs. 2 and 3, circui' ~ozrd mounting arr2ngement 100 comprises cne or more substantially ~ectangular 2~ circuit boards 101 and 102 (a total of four such bo2rds being ::-shown in Fig. 2). Circ~it boards 101 are held in a spaced apart --par~llel relationship with resp~ct to each other by means of ---supports 103. Circuit bc2rds 102 are spaced apart from boards 101 .-by means of spacers 105.
Supports 103 each ccmprise an elongated rod having mounting t,,, means, such as intern~lly threaded studs 107, formed as part of each end of the rod. Each support further includes at least a pair of flat areas 109 disp~sed parallel to each other and adjacent to the mounting means of each end of the support. As ---shown in Fig. 2 these flat areas 109 can take the form of a six sided surface formed adjacent the mou~ting means of the supports 103. Additional parts of flat areas 109 can be formed along ...... .... ............ , .... ....... .................... ... . ,, , ,,, .,,, .. ,, .. , .. , ......... .. -su~p~rts 103 in case support of boærds 101 is needed at some point intermediate the ends of s~??orts 103.
In a preferred ærrange~ent supports 103 are disposed substæ~tially parallel ~o the longitudin 1 axis of an instrument housing 500 (sh~ in more detail in Fiss. 12a-12c). One or more circuit boards 101 are mounted to flat areas 109 of supports 103 --through æny ccnventional f2stening means, such æs the threaded fasteners 111 sh~wn in Figs. 2 ænd 3. Supports 103 and circuit boards 101 are dimensioned along their longer sides such that -lQ mounting means 107 project outward from the perimeter of circuit .~
boards 101. Circuit boards 101 and 102 are also dimensioned along their shorter sides to be less ~han the inside diameter of instrument housing 500 with circuit boards 102 being slightly narrower in width than ~oards 101..... The spacing between support ~-faces 109 determunes the spacing between facing boards 101 and is .:-chosen to prevent arcing fro~ occurring between the circuits etched on the facing boards. ~-Spacers 105 are sh~wn as short hollo~ internally threaded cylindrical studs which enable the mounting o~ one or more additional circ~it boards 102 to the first pair of circuit boards by means of threaded fasteners 106. Obviously, supports 103 of ~=
the elongated rod type can be substituted for the stu~ type E
spacers 105. Spacers 105 are merely shcwn ~to -~3nonstr~te that F
spaoe r means of other types can be ~!ced successfully in combination with supports 103.
A completea circuit board and support assembly, oomprising at least one circuit board 101 and a pair of supports 103 is then -mounted to a pair of mounting plates 113 and 115 as shown in Figs.
2 and 3. Mountins plates 113 and 115 have a substantially E:
circular shape and are dimensioned to fit within instrument E
housing 500O Mounting plates 113 and 115 may further include one F::
or more openings formed ~herein for accommodaiing wirins, such as t-:
a wiring harness 117 as shown in Fig. 3. Wiring harness 117 has E
been o~itted from the o.her drawing figures for the sake of clarity. Each of the mounting plates 113 and 115 further incl~des at least a pair of cp~nings adapted to receive mounting means 107 --:
of supports 103. --~ZiL~10g ' ` '' Mounting plates 113 a~ 115 are esse~bled to mounting means 107 of sup~orts 103 through respective op ninss 116 and 118 formed in pia.es 113 and 115. Preferably, mo~nting means 107 are threaded and mounting pla~Qs 113 and 115 are secured to the mounting mear~ by conven~io~al threa~ed fasteners 119.
In the embodim~nt shown in Figs. 2 and 3, mounting plates 113 and 115 are shcwn as separately mountable ccmponents. This enables o~e or more subst2ntially circular circuit boards 121 to --be mounted between rear mounting plate 113 and an instrument lQ housing end cap 123. Hcwever, in some instan oe s it may ke ~sired to mount the circuit board support assembly directly to end cap 123, as shown in ~ig. 4. In this case mounting means 107 of -supports 103 can D_ mcunted clrectly to an interior face 12; of end cap 1 3, or can be spaced apart therefrom by means of a pair of hol~ow intern~lly threaded spacers 127. A pair c~ threaded bolts 128 are used to secure end cap 123 and spacers 127 to supports 103. Thus, in the embodiment shown in Fig. 4, end cap 123 acts as one of the mounting plates for the circuit board ~-support assembly. ':
Likewise, mounting plate 115 can serve a dual purFose, namely ~:
as a base to which an analog~digital indicator assembly, such as ~--those shown in Fig. 1 and Figs. 6-10, can be mounted. Plate 115 can optionally be secured to housing 500 by m~ ~ of radially disposed threaded fasteners 124 (see Fig. 3). L
End cap 123 is of ccnventional design and is dimensioned such that faoe 125 fits se~urely within housing 500. End cap 123 in d udes a plurality of feed-through type electrical connectors 1~9 to which the wires o~ wiring harness 117 are oonnected.
Connectors 1~9 are surroun~ed by a socket shroud 131 formed as part of end ~ap 123. Connectors 1~9 and shroud 131 are of ccnventional design for use with plug-in or screw-on type wiring harnesses as is well knc~n in the aircraft instrumentation art.
End C'2p 123 is secured to housing 500 using conventional fastening means. For example, housing 500 can be internally threaded to --receive complementary threads formed ~n a mating portion of end cap 123 or a bayonet-type mounting arrangement can be used.
Alternatively end cap 123 is secured to housing 500 using radially --2~ Q9 dis~sed th.eadeà bolts or by means of soldering. If desired, a sasket-t~e seal, such as cn O-ring 133 can be provid~d around the periphery OL f aCe 125 .
~hile th~ mounting arrange~en. of Fig. 2 s~.-s a to,al of --S four rectangular circuit ~oards being mounted in a stacked fashio~, it is to be understood that fe~er or greater nu~bers of --circuit boards may be so arranged, as desired. For example, Figs.
3 a~d 5 show three circuit boards 101 and 102 mounted together.
Fig. 4 sh~s a pair of circuit boards 101 mounted in a spaced lQ apart fashion by supports 103, the su~ports in turn being attached -.
.o a mounting plate 115 and end cap 123, the end cap acting as a -mounting plate in this e~bodiment. -In Fig. 5 two circuit boards 101 and one circuit board 102 -are sh~wn mounted to su~ports 103 and spacers 105. The circuit r board and support asse~bly is then mounted to mounting plate 115 and end cap 1~3 as described above with respect to Figure 4. Due .. -to the modular arrangment a circ~lar circuit board 121 can be readily mounted between end cap 123 and the rectangular circuit ~
board mounting assenbly by means of hollow spacers 127 ana 130 E--through which threaded bolts 128 are run from end cap 123 to r~-intern~lly threaded m~ounting means 107. If desired, an elcnsated rod spacer 134 can be provided between mounting plate 115 znd end ~-cap 123 ~or a mounting plate 113) to provide even _~rther rigidity r to the circuit board and mounting plate assenbly.
Of course, other numbers and ccmbinatior~ d rectangular and/or circular circuit boards can be provided and would be obvious to one skilled in the art. In its mininum configuration ~-one circuit board 101 is mounted to a pair of suçports 103 by fasteners 111 and then mounted to mounting plates 113 and 11~, or F~'"
alternatively to end OEp 123 and mountins plate 115.
Several advantages flow from the above-described circuit E-board mounting arrangements. These arrangemer.'s help to isolate F:::
the rectangular circuit boards frcm vibration impinging on the ~-instrument housing as there is no direct contact or mechanical co~nection betwe~n the housing and the circuit boards. In additicn, the described arrangements are extremely flexible in that multiple circuit boards of both rectangular and circular .........................................................
Zl~109 ` I
-- 10 -- .
shape can be easily ~cunted tcsether in one com~act zssembly. In additicn, the descri3ed circuit ~oard mounting ~rranse~ents facilitate the use of elec.rical ccm~onen s and circuits, su^h as large scale integrated circuits aad r,icroprocessors, which ære --otnerwise too large to mc nt o~ a ccnventionAl circular circuit --board. As will be readily appreciated, a greater num~er of electrical components such as those denoted as 135, 137 and 139 in Figs. 2-5 can be mounted on a rectansular board as opposed to ::
ccnventional circular circuit boards (which of necessity can be no larger in diameter than the inside diameter of the instrument housing). ~y stacking rectangular circuit boards 101 and 102 only a minimum amount of interoonnecting wiring (such as flexible cakles or plug-in type terminals 141) need be used to connect ~
circuits on adjacent b~ards lOi and 102, as oompared to the large ~-amount of interconnecting wiring which is gener~lly needed in conventional stacked circular circuit board mouncing arrangements.
r'~
The described a~rrangements also reduce considerably the amount of labor involved in wiring and assembling the circuit boards into an r~'' integrated package for use in a cylindrical instrument housing.
Thus, the present invention affords not only a simple ~d vibration-resistant mounting for circuit boards but substan~ially reduce labor and material costs through greatly reduced E
requIrements for interconnecting wiring.
r A further advantage is that the modular ~ature of the prese~t r' invention enables all the circuit boards and associated F-.-electronics to be built as a subassembly separate and apart from ~-an analog and/~r digital instrument display (shown in Figs.
~--6-10). The flexibility inherent in these mounting arrangements ~-~
enables such circuitry to be tailored to an individual customer's -~
specifications for use with any type of display, whether analog, digital or a combination of both. The ab~ve-described --arrangements also allo~ cptimum use of the limited space available ~-in a cylindrical instru~ent housing while acoom~odating sophisticated electronic circuitry, all while providing a simple, easy to manufacture and rugged support for such electronics and -:~
associated display mechanisms.
2~ 9 ` I
3. Modul ar anal4q/digital instrunent display With reference ~io ~ig. 6, there is sn~n a modul~r Ga_klighted an210g/disital instrument aisplay ~sef ul with the 2~0ve-d~scribed cir~lit boærd mounting arr~rlgPmPnt. Display asse~bly 200 includes a base 201 (which .or exa~?le can be ,mounting plate 115 as shc~ in Figs. 2-5) to whicll an analog meter movement 203 is mounted in any convenient fashior.. ~leter move,~ent 203 is of conventional and well known d~sign and m2y for example cQnprise a ving coil mPcharlism of the D'Ars~val t~rpe. Meter , -movement 203 includes a rotatable sh ft 205 extending in a direction substantially parallsl to the longitudinal axis of an instr~nent housing 500 (as sh~t~n in ou~ine in Fig. 8). Meter shaft 205 includes æn articulated portion 207 formed at one end thereof t~ which an ~nalog dial p~inter 257 is mechanically E::-cor3nected. A bracket ænd spacer assembly 209 is mounted ,o the housing of meter move~nent 203 (or, alternatively, mounted to base 201). The meter housing includes a pair of ~ unting bosses 210. L
One probl~sn associated with asse~bling an analog meter mechani~n is the fact that the p~inter 257 generally must be attached to meter shaft 205 prior to mounting any other ccmponents F=
such as an 2na:Log dial, digital display or ~acklighting means.
This is because the meter mechanism must be balanced with the t--~pointer attached. Such a re~uirement prevent~s ,embly of the r--various analog cnponents in a straightforward manner. The foll~ing arrangement is intended to overccme this problem.
A circuit board 211, which for example is sub6tantially circular in shape and adapted to fit within the cylindrical b instrunen'c ~using, is mounted to bracket assernbly 209 as t described in more detail belc~. Circ~Lit board 211 includes an t=
opening 213 and slot 214 adapted to receive rotatable shaf t 205.
As sh~n more clearly in Fig. 7, circuit board 211 includes a ~F-plurality of electrical contacts cnprising plated through , -openings 215 fo~:med in circuit ~ard 211 to which the leads o~
digital display sockets 217 are attached in a conventional manner, such as by soldering. Sockets 217 are adapted to receive the leads of digital display readouts 219, which for example may be of the incandescent or light e~nitting diode types. -....... ........................................................................ ........ ....
- ........................................................................................................ ...... . . ....
zla~os -~ I
;
l~un'ed 'o circuit board 211 is light collecting plate 221.
Light collecting pla.e 221 is adapted to fi. wi~hin cylindric21 housing 500 and is forr-d from a subst~atially clear light collecting ma~erial su~h as that hr~ under th~ trademark PLEXIGL~S @. Light collec.ing plate 221 includes a first opening 223 adapted to receive digital display 219 and a second opening 225 and slot 226 adapted to receive the articulated portion 207 of ---meter shaft 205. The first o~ening 223 further includes a lip or -recess 227 formed therein for receiving a display filter 229.
lQ Disposed within opening 225 is one end of a light pipe 231 formed -- -frcm a light tran~nissive material such as that used for light -collecting plate 221 or of any one of a number of well-knc~n fiber optic materials ----Light collecting plate 221 further includes a recess 233 --fo~med in a portion thereof for receiving illumination means 235 and for enhancing the collection of light therefrom by light --:
collecting plate 221. Recess 233 also includes a portion adapted ---to receive the other end of light pipe 231 and to dispose it adjacent illunination means 235, as shc~wn in Fig. 8. Illumination means 235 cQ~prises, for exa~ple, a pai~ of incandescent lamps mounted to a circuit board 237. r,,_ Dial 245 is mounted to light collecting plate 221 ty threaded r~~
fasteners 247 and 248. Dial 245 is forme~ from a light L
transmissive or translucent material and includes one or more dial markings 249 proviaed therecn. Dial markings 249 are preferablyF::=
formed ~y screening selected areas of dial 245 and covering thek remainder with an opaqye c~ating such as flat black paint. ~-Alternatively, the dial m2rkings can oomprise opaque (dark) areas ormed on a transluoent dial. The dial and markings c2n also be forme as an integral part of one face of light oollecting plate 221.
Dial 245 includes an opening 251 formed therein which is adapted to expcse display 219 to view through filter 229 when the analog/digital instrument is assembled. Dial 245 also includes an opening 253 and slot 255 for accomodating the articulated end 207 :-....
'' of meter shaft 205. Dial pointer 257 can include an cp2que lisht reflective p~rtio~ 259 formed thereon (from whi.e paint, for ................................... ,,,,,,,.. ,...................... :: ::::.. :.-r~ ~LZ~L~lQ9 !
ex~mple) for selectively blocking or directing light e~ission from pointer 257 alc~g selected xrtions thereof. ;
The analo~Jdigital ins.r ment is asse~bled as folio~s. ~leter mechanism 203 is fasteneà to base 201 and brackets 209 are S attached to meter mechanis~ 203. Dial pointer 257 is attached -(such as by adhesive ~onding) to articulated end 207 of meter shaft 205. Spacer 239 is attached to circuit board 211 via threaded fastener 240. Circuit board 211 (to which sockets 217 have been previously soldered) is slip~ed over pointer 2;7 and :--lQ shaft 205 via slot 214 and seated on bracket spacers 209 and :--bosses 210 of meter mechanis~ 203. A pair of threaded studs 241 are used to secure circuit bo2rd 211 to bracket sp~cers 209.
Light pipe 231 is fitted into recess 233 provid~d in light collecting plate 221. The light pipe is retained in recess 233 by '-mounting lall~ circuit board 237 to light collecting plate 221 via -.
a pair of threaded fasteners 2430 ~-Light collecting plate 221 (with 12mp circuit bcard 237 and light pipe 231 assembled thereto) is slipp~d over pointer 257 and r~
meter shaft 205 through slot 226 so that articulated portion 207 t.
of shaft 205 is located just below light pipe 231 in opening 225 .~
of the light collecting plate (Fig. 8). The light ccllector ~-asse~bly is seated on the two mounting studs 241 and is fastened to meter housing bosses 210 via a pair G~ threaG ~ fasteners 244 F
which are passed through openings provided in the light oollecting E
plate, circult board 211 and spacers 242 (staked to circuit board E
237) . Mounting studs 241 are then tightened to fiDmly secure ~-circuit bo2rd 211 to bracket spacers 209.
Digital display readouts 219 are plugged into scckets 217 and polarizing filter 229 (if a self-illuminated digital display is 'F~-used) is fitted into recess 227 provided in light oollecting plate ~:
221.
Dial 245 is fitted over pointer 257 through opening 251 and '--over articulated portion 207 of meter shaft 205 via slot 255 -:-provided in dial 24s (similar to slok 226 provided in light collecting plate 221) so that the artlculated portion of the meter --shaft is disposed in dial cpening 253 (Fig. 8). In cases where --pointer 257 is too large to fit through opening 251, slot 255 can ~-~ 121~ 9 ~ !
i be, brought all the way out to the circu~nfere!lce of dial 245 (see Fig. 9).
~o threaded fas.~ ers 247 are placed thro~.2gh o?enir,ss provided at a2proximately ~he 8 o'clock and .~ o'clock positions of dial 245 and ligh, colle~ins p' ate 221 and fas.ened to mounting studs 241. Threaded fastener 248 is passed through an opening provided at a~?ro~:im.2tely the 12 o'clock E~osition of dial 245 and fastened to a similar threaded opening pro~ided in light collecting plate 221. Threaded faste, er 250 is passed through lQ openings provided at a?proximately the 6 o'clock position of dial 245 and a lc~e~ portion of filter 229 and is fastened to spacer 239.
Once the analog/digital instrunent asse~nbly is cnpleted it can be readily attach~d to the circuit board mounting arrangement described earlier and inserted into cylindrical housing 500 as shc~n in Figs. 8 and 12b. A clear wind~ 505 is disposed between a retaining ring 503 which is fitted over one end of cylindrical housing 500. Ihe digital display circuitry and analog meter movement are readily connected to excernal signals or to signal 2 0 processing/conditioning circuitry (such as that described ab~ve with respect to the circuit board mounting arrange~nent) in any canventional f shion, such as thrcugh connectors 129 of end cap 1?3.
~t will be al~preciated that the above-described arrangement ~nables a baclclighted analog/digital display, including an ill uminated dial pointer, to be readily ass~nbled without interference occurring between the digital display ccmFonents and the analog mechanism and pointer . Bac clishting of dial 245 is provided by the light frcm ill unination means 235 which is collected and transmitted through light collecting plate 221. The light fran illum~nation means 235 is also transmitted to dial pointer 257 via light pipe 231.
If display 219 is o the self-il1uninated type no edge-lighting is needed. Indeed, edge-lighting of such a self-ill ~ninated display ~uld re~uoe display contrast by washing out the illuminated digits of display 219. To prevent this fr~n happening, and to enhanoe display contrast for such self-.......................................................................... _ .... . = . .......... . ... ... .
2~09 illu~ina.ed displays, filter 229 is of the polarizing type which acts to reduce the effect 0c anbient light on the ex2osed face of digital display 219. In cddition, the edge of recess 233 ls coated with 2n opaque m3.Qri21, su~h as black Faint, to prevent lisht transnitted througn 11sht collecting plate 221 from reaching the exposed faoe of the digital display. Of course, if a non-self-illu~inated display, such 2s a liquid crystal display, is used and it is desired to edge light su~h a display, the edge of recess 233 can be left clear and polarizing filter 229 can be o~itted.
The d~scribed analog/aigital display arrangement thus enables a simple yet versatile ins~rument to be built all in one compac~ - -unit which can be fitted into a cylindrical instrument housing. ~-As the various c~nponents are modular, the digital and an210g portions of the displays can be assembled (or disasse~bled for -~-repair) without interference with one another. This greatly reduces the time and labor involved in manufacturing such displays and th~s results in a low cost, yet rugged analog~digital display.
Fig. 9 sh~ws an alternative embcdiment of an analog/digital display 300. ~isplay 300 is in many respects similar to that ~
2Q shcwn in Fig. 6 and similar o~nponents are denoted using similar ~-reference nunerals. ~:
In Fig. 9 a non-self-illuninated display 301 is shown, such as a liquid crystal display. Such displays may b- c the leadless F
type, as sbown, or may include leads or pins for mounting to a s x ket ox directly to a circuit board such as previously described E
with respect to Fig. 7. If 2 leadless unilluminated display such .-as 301 is used, some means for connecting contact pads fonmed on the display with etched tenninals 215 foxmed on the surface of circuit board 211 must be provid~d. Such contact means can take ~-=
many forms. Hcwever, in the preferred emb~diment such oontact ~::
means take the form of tw~ contact strips 303 of elastomeric dielectric materi.l in which are embedded (or formed on a surface ,F'',':
thereof) a plurality of spaced apart conductive portions. Such types of elastomeric o~ntact strips are well kncwn and include thcse sold unde~ the trade nane ZEBRA~
As contact strips 303 are scmewhat flexible scme means for --.
supporting them must be provided be.ween display 301 and terminals f~ lZ~ 9 - I
!
215 of circuit ~oard,211. To this end, a guide 305 having two transverse slots 307 fo~d therein is mounted to circuit board 211 b~ me~ns o' fasteners 309. I~ount 311 for illumination means 235 also inoludes a pair of transverse slots 313 adapted to receive and suide portio~s o' con.ac, strips 303.
Light ool1ecting plate 315 is some~hat similar in arra~gem~t to collecting plate 221 (Fig. 5) and incluaes a recess 317 and a pai~r of transverse slots 318 (aligned with slots 313 of board 311) which are adap.ed to receive display 301 and contact stri~s 303, 1~ respectively, and a second opening 319 adapted to receive light pipe 231 and meter shaft 20;.
Analog/digital display 300 is asse~bled as follows. Analog meter mechanis~ 203 is unted to base 201 and single spacer bracket asse~bly 329 is fastened to the housing of mechanism 203.
-15Circuit board 211 is slip~ed over shaft 205 through radial slot -,' 214 and is secuLed to bosses 210 and bracket spacer 329 by means --of three threaded mounting studs 241. Contact strips guide 305 is ---mounted to circuit board 211 via a pair of ,hreaded fasteners 309 which fit into threaded bushings 310 mounted to circuit board 211.
20Light pipe 231 is plaoed in recess 316 (si~ilar to that shown ~-in Fig. 8) formed in light collec.ing plate 315 with one end ~,-disposed in oFening 319 of plate 315. L2~p mount 311 (to which rr lamps 23S have been previously attached) is fi,'~d to the rear ~=
face of light collecting plate 315 with transverse slots 313 of mount 311 aligned with slots 318 of plate 315. The light t 25col1ecting plate and lamp mount are slipped over shaft 205 and E
pointer 257 (which has been previously attached to shaft 205 in order to allow the meter mechanism to be balanced) via radial F
slots 321 and 323 formed in plate 315 an~ lamp mount 311, respectively, ~r 30Light collecting plate 315, light pipe 231 and lanp mount 311 ~,-are secured to the upper pair of mounting studs 241 (previously t`
secured to b~sses 210) by means of threaded fasteners 329 which t fit into recessed opemngs formed in light collecting plate 315.
Contact strips 303 are inserted through slots 318, 313 and ~'-35307 of the light collecting plate, lamp mount and contac, strips guid~, respectively, until they are in oontact with etched '~' ~21C~`~109 ~ !
I
contacts 215 formed on circuit board 211. Liquid crystal display 301 is plaoe d into recess 317 of light oollecting plate 315 until its leadless con~acts ab-t the edges of co~tac. s.rips 303.
Dial 245 is sli~ed over cointer 257 and shaft 205 in a similar fashion as described ~ith respect to Fig. 8. Dial 245 is mounted to light collectlns plate 31~ by means of three threaded --fasteners 325 and one threaded fastener 327. F~steners 325 are threaded into dial 2g5 and light oollecting pla,e 315 at approximately the 8 o'clock, 12 o'clock and ~ o'clock positions, while fastener 327 is threaded through dial plate 245, light collecting plate 315 and lamp mount 311 2t approxim2tely the 6 o'clock position, and is secured to mou~tins st~ 2Al. As opening 251 of dial 245 is dimensioned slightly smaller than the outer periphery of display 301, the display is securely cla~ped into contact with contact s.rips 303 by àial 245.
With the above-describ~d arrange~ent a non-self-illuminated digital display, such as 301, is edge-lighted by the light frcm illumination means 235 that is col1ected and transmitted through light collecting plate 315. In addition, lisht collecting plate 315 acts to backlight dial 245, and dial pointer 253 is - --illuminated by light from illumination means 235 which is -r transmitted through via light pipe 231 as described above with respect to Figs. 6-8. In addition, the _ov~-described arrangement readily accommod2tes digital displa~s of the leadless type (whether self-illuninated or not) in a ccmpact, rugged and easy to assemble package.
Fig. 10 shows yet another technique for mounting leadless digital displays in an analog/digital instrunent, and further shows an alternative technique for attaching a dial pointer to an 't'.
analog meter shaft (Fig. 11). Parts and ccmponents in this emkodiment which are commcn to those in the aforementioned t embodlments are denoted using identical reference numerals. r''-Threaded mounting studs 409 are used to nu~nt circuit board ~-211 to spacer 423 and bosses 425 af meter movement 203, which in turn is mounted to b~se 201. Circuit board 211 can be connected :-to external signals throush any conventicnal means, such as by means of a wiring harness 421 (sh~wn Fartially in ~ig. 10).
~ ~L21~1Q9 i Le2`1ess display. 301 is ~.~ounted to etched te~ninals Z15 formed on circuit bo2rd 211 via elastomer-type contact strips 303. Instead of slotted cuiae 305 and la~p mount 311 (Fig. 9) a --spacer 401 is dispcsei set~n circuit board 211 and display 301.
A display housing 403, having an oæ ning 40; formea therein for -exposing display 301 .o vie~, is seated against spacer 401 and fastened o circuit board 211 by means of fasteners 407. Display housing 403 acts to cla~.~ disital display 301 firrly against contact strips 303, thereby causing contact strips 303 to be .. -lQ securely urged into contact with contact pads formed on display 301 and etched contacts 21; of circuit board 211. A pair of .-gaskets 407 are also provided between either end of display 301 -:
and a surface of spacer 401. The rear of display 301 dbes not contact spacer 401. -After digital display 301 is assembled to circuit board 211, dial 24~ is secured to studs 409 by a pair a threa.~ed fasteners -411. Nanrilluminated pointer 413, which includes a threaded portion 415 along shaft 416, is screwed into a .~."plementary .. -threaded bu.shing 417 disposed in rotatable meter sl~aft 419 of meter mechanism 203 as is more f~-lly described belcw with respect ,t.
to Fig. 11.
In the e~cdiment shown in Fig. 10, no illumination means for ~=
the digital display or backlighting means for the ~ial and pointer l_ is provided. ~.owever, it will be understo~d that such illumlnation and backlighting means c~uld be readily incorporated into this em~odiment. For example, display housing 403 could be fonmed fr.om a light tsansmissive and collecting ~aterial and E
illuTination means (such as 235 shc~n in Fig. 9) could be disposed r~' adjacent thereto to edge-light display 301. Alternatively, a ~.
light collecting plate such as 221 (Fig. 6) or 315 (Fig. 9) could ~:
be incorporated to provide edge-lighting of display 301 and ~
bac~lighting of dial 245. If an illuminated pointer is desired, .-pointer 413 could be ~eplacec. with an i11uminat.~d pointer such as Z57 (Figs. 6 or 9) and light pipe 231.
The display mounting arrangement of Fig. 10 adva.ntageously enables a leadless digital display and associated contact strips to be securely clamped into contact witn terminals ronmed on a :
:121~`~Q9 .--', circuit board. As is apparent, the described arrange~ent enables the dis~lay to be moun.es without interference with the analog meter mechanis~ or me.er shaft. ~he screw on Fointer simplifies assembly where illuminatio~ of the poi~ter is not needed.
~Sore par,icularly, the use c~ screw on pointer ellminates the need for slots or cut-outs in the dial which may detract from the appearan oe of the dial. Yihile the construction of a screw-on pointer would appear to be a straightforward proposition, several problems arise. First, the meter shaft 419 generally is formed from extremely thin-walled hollcw tubing (usu lly of a light-weight material such as a soft-grade of aluminum) which is not ---easily internally threaded due to its thin~ess. Thus, if more ~
than a slight anount of force is applied to shaft 419 it will .-likely bend or distort and des',roy its usefulness as a meter L-:
shaft. Second, in attaching pointer 413 to meter shaft 419 it w~uld ~e desirable if the pointer could be lc,cked in a desired angular position with respect to meter shaft 419 and dial 245.
Finally, the distance from the pointer to the face of the dial ~
should be adjustahle to allow for slight variations in tolerances E
(such as ~hickness) of the various components. L:--To this end, the screw-cn pointer shown in the detail cross-secticn of Fig. 11 is constructed and assembled as follows.
Bushins 417 is internally threaded and includ a collar 418 F
formed on one end thereof. Bushing 417 is fitted into one end of ~-meter shaft 419 with the collar abutting the end of the meter c shaft. Bushing 417 can be formed from a thin-walled, yet easily ~t machinable material (such as a machinable grade cf aluminum) and serves to stiffen the end of meter shaft Al 9 into which it is inserted without adding substanti~l~y to the weight or inertia of t-shaft 419. Bushing 417 is held within meter shaft 419 by a dab of adhesive which is ap~lied to the outer surface of the bushing -,-prior to its insertion into the meter shaft.
Pointer 413 includes an opening 414 enabling the pointer to be sliFped over pointer shaft 415 until it is seated against the -::
underside of shaft head 429 wnich is c~ a di~neter larger than the shank of pointer shaft 415 and pointer oFening 414. Pointer 413 .
is secured to shaft 415 and head 429 by conventional fastening .::
.. , - -- .. ............................................................................... ... ..... . .. . .
121(~ )9 me~ns, such as adhesive bc~ding. Lcc~nut 427 is then threaoed over tl~e threaded portion o~ x inter shaft 415.
Th~ digital dis?lay ænd dial are assem~led together as described with respect to ~ig. 10. The ~hreaded portion of pointer shaft 415 is passed thro~lgh opening 253 of dial 245 ænd threaded into bushing 417 until pointer 413 is at the desired distance frcm dial 245 and at a desired angular position with :,, respsct to the dial. The pointer is then secured in position to ,' meter shaft 419 by turning locknut 427 ~by means of a pair of :
1~ tweezers, for ex3mple) until it contacts collar 418 of bushing 417. If desired, the locknut can be permanently secured by --ap?lying a dab d adhesive at the point where it and p~inter shaft 415 contact. -' As is aFparent, the oescribed screw-on p~inter enables the angular position and distan oe of the pointer with respect to the diaL to be readily adjusted. The threaded bushing inserted into the meter receives the threaded pointer shaft and acts to stiffen '-''' the walls of the meter shaft to prevent bending or distortion thereof when the pointer is threaded to the meter shaft. ',', As mentioned earlier, the circuit b~ard arrange~ent of Figs. ,--2-5 and an log/digital display arrangements of Figs. 6-10 are -~
designed to fit within th~ confines of a standard (e.gO 2 inch) dia~eter instrunent housing 500 as shown in .gs. 12a-c. A t typical anaLog/digital instrument faoe is show,n in Fig. 12a. --Analog/digital instrument 200 and circuit board mount 100 are r-sh~wn disposed within cylindrical housing 500 in the cross~
sectional view of Fig. 12b. Fig. 12c shcws a rear view of housing ~-, 500 with end cap 123 secured in plaoe . ~-As briefly mentioned earlier, circuit boards 101 and 102 can oontain electronic circuits and ~ ponents for driving the digital ,t~, displays and performing scaling and signal processing functions for the analog meter mKve~ent. An example of one type of ,-ccnventional circuitry which can be used with the various --embodiments of the present invention is shown in block diagr~
form in Fig. 13. '' The foregoing description is not intended to ~e limitive or ', exhaustive but rather illustrative of the invention wnich is '-,',',-defined ~y the ~aDpended claLms. -'' ......................................................... ...................................................................... .
. .
While such analog instruments have found widespread use throughout the aerospace industry such instruments have a major drawback in that an analog instrument must be interpreted by the ~' - 1 -L21~1~9 ~
!, human observer. Such o~servations are prone to error, especially in view of the literally o~zens of such instruments ~hich must be constæntly scanned in modern cx~erciæl and military aircraft.
In order to obviate these probl~s .here h2s been a demænd for more precise display of critical operatins paraDeters such as ~-can be provided ky digital displays. For hL~æn engineering purposes, it is generally desirable to combine an analog display - -with a digital display of a critical cperating ?arameter. -:
Severe environ~ent~l constraints are placed o~ æny proposed lQ analog/digital instrument d~sign. Such instru~ents must be rugged, accurate and relia~le even when subjected to extremes of temperature, pressure, and vibration as is comncr. in aircraft and aerospace environments. In addition, military and com~ercial standards dictate that most panel instruments be circular in shape and fit within standardized openinSs (diameter and depth) in an r,",,' instrument Fanel. A problem arises in that the large nu~ber of ~
electronic components needed to drive a digital display or used for signal conditioning of an analo~ display will often fill the _-spaoe available behind the mounting panel without leaving sufficient room for the analog (mechanical) movement. The r~",.
complexity c~ ccmponents and lack of space within the instrument ..
housing also make it diffic~lt to assemble the digital display and :
analog meter movement together without interfe ~lce with each other and to readily interoonnect oomponents on adjacent circuit boards. Such difficulties increase manufacturing and repair ~-cost50 In addition, the oamplexity of such displays makes it difficult to a& pt an instrument to different lighting requirements and display types, e.g. light emitting diode (~E~), liquid crystal (LCD), incandescent displays cf the integral lead ~::
or leadless types which are edge-illuminate~, backlighted or ~-unilluminated, for example. ~-A particular pro~le~ associated with assembling the analog~:
display components resides in attaching the pointer to the analog meter shaft. In some instances it is desirable to have the --pointer attached after a~l other cGm æ nents, including the dial, have been mounted to the housing of the an~log meter movement.
This has the advantage that only a single central opening in the -~Zl~9 dial and associated internal components is required to enable these components -to be slipped over the meter shaft and assembled to the meter housing. Thus no radial slots or openings are needed which would detract from the appearance of the dial.
However, several problems arise in attaching a pointer to a meter shaft. The angular position of the pointer with respect to the meter shaft and dial should be readily adjustable.
The distance of the pointer from the front surface of the dial should also be adjustable to allow for slight variations in the thickness of the dial and associated components. In addition, as meter shafts are generally formed from light-weight extremely thin-walled tubing (to reduce weight and inertia) the method of attaching the pointer to the meter shaft should not place any substantial stress on the meter shaft, else the meter shaft may be twisted or otherwise distorted.
There is thus a need for an improved arrangement for mouhting a pointer to an analog meter shaft which places little stress on the meter shaft during assembly and which further enables both the angular position and distance of the pointer relative to the dial to be quickly and easily adjusted.
There is also a need for a compact and modular analog/
digital instrument which is adaptable to various types of displays and lighting techniques and in which the digital display can be assembled or disassembled without interference to the analog meter movement in order to facilitate manufacturing, and to thus reduce assembly and repair costs.
Summary of the Invention .
It is a general object of the present invention to provide an improved electrical measuring instrument.
This and other objects are attained, in accordance with a broad aspect of the invention, by a modular analog/digital instrument display for use in a cylindrical housing including:
a base adapted to fit within said housing; an analog meter movement adapted to fit within said housing and mounted to said base, said meter movement including a rotatable shaft having a portion thereof extending in a direction substantially parallel to the longitudinal axis of said housing; a circuit board adapted to fit within said housing and mounted in aspaced-apart relationship to said meter movement, said circuit board including electrical contacts formed on at least a portion thereof, said circuit board further having an opening formed therein for receiving said meter movement shaft; a digital display; means for mounting said digital display to said circuit board including means for electrically connecting electrical contacts of said digital display with said contracts of said circuit board, an analog dial adapted to fit within said housing and mounted to said circuit board, said dial including a first opening for receiving said meter movement shaft and a second opening for exposing said digital display to view; and a dial pointer mounted to the end of said meter movement shaft extendlng through said dial, said dial pointer being arranged adjacent to a face of said dial.
Brief Description of the Drawing Figures These and other features and advantages of the present invention will be readily understood with reference to the following detailed description of the preferred embodiments of the invention, when taken in conjunction with the accompanying drawing figures wherein;
Fig. 1 is an exploded perspective view of the circuit board mounting arrangement and modular analog/digital instrument displays for use therewith;
.~ 121~ 9 ~- 1 Fig. 2 is an exploded perspective view of another form of circuit bc2rd mounting arrang~ent in accordæ~ oe with the prese~t invention; -Fig. 3 is a partial cross-sectional view of o~e form of circuit board mounting arransement;
Figs. 4 and 5 shcw ~odified versions of the circuit board mounting arrangment of Fig. 2;
Fig. 6 is an exploiei perspective view of one form of backlighted analog/digital instrument display for use with the lQ circuit board mou~ting arrange~ents shown in Figs. 2 through 5; -Fig. 7 shcws one for~ of digital display mounting for use wi~h thR instrument of Fig. 6;
Fig. 8 is a cross-sectional view ta~en along plane 8-8 of Fig. 6; ~
Fig. 9 is an exploded perspective view of an alternative form of backlighted analog~digit~l instrument display wherein the _-digital display is eage-lighted;
Fig. 10 is an explcded perspective view of an analog/digital display showing an alternative form of mounting for the di~ital dis~lay;
Fig. 11 is a detail cross-sectional view taken alons plane A-A of Fig. 15 showing details of construction of a screw-on ~-poin~er; 1-Figs. 12a, b, c respectively show a front plan ~iew, a side ~--cross-sectional view and a rear plan view c~ a typical instrument housing in which the devi oe s of Figs. 1-10 are designed to be mounted; and E
Fig. 13 is a block diagram of circuitry representative of that which can be mounted to the circuit board arrangements of Figs. 2-5 and which is useful with t~e analog/digital instruments ~-of Figs. 6-10.
Detailed D scr~ption of the Preferred Embodiments ~-1. Overall system arrangement 3~ Fig. 1 shcws the overall relationship of the circuit board mounting arrangement, deno~e~ generally at 100, with three tvpes ... .. . . . . .. .. .............................................. --.. -- -- -- - - .. ............................................ ..
Zl~9 of modular analo~/digital instrument display zssemblies, denoted æs 200, 300 and 400. -~ore paLr.icularly analog~digital display zsse~bl~ 200 --includes a self~ uminated digital dis?lay (such æs .hat formed frcm light emitting dio~es or incandesoe nt lam?s) æ~d an --illuminated dial ænd pointer. Display asse~bly 300 features a non-self-illuminated display ~such as a liquid crystal display) and means for edge-lighting this display ænd backlighting an analog dial and pointer. Display æsse~bly 400 features a 1~ scre~on-pointer and shcws an technique for mounting a leadless digital display to a circuit board for use with æn ænaloq/digital instru~ent assembly. -:
As will be described in more detail belc~, the circuit board mounting arrangement 100 and modular display arrangements 200, 300 t and 400 enable a ccmp~ct and rugged 2n210g/digital aircr2ft or aerospace instrument to b~ constructed which is designed to fit within t~e confines of a small diameter (e.g. 2 inch) cylindrical instrument housing, such as is shc~n in Figs. 12a - c.
Each of the above mentioned assemblies will ncw ~e described L--in more detail.
2. Circuit board n~ounting arrangment With reference to Figs. 2 and 3, circui' ~ozrd mounting arr2ngement 100 comprises cne or more substantially ~ectangular 2~ circuit boards 101 and 102 (a total of four such bo2rds being ::-shown in Fig. 2). Circ~it boards 101 are held in a spaced apart --par~llel relationship with resp~ct to each other by means of ---supports 103. Circuit bc2rds 102 are spaced apart from boards 101 .-by means of spacers 105.
Supports 103 each ccmprise an elongated rod having mounting t,,, means, such as intern~lly threaded studs 107, formed as part of each end of the rod. Each support further includes at least a pair of flat areas 109 disp~sed parallel to each other and adjacent to the mounting means of each end of the support. As ---shown in Fig. 2 these flat areas 109 can take the form of a six sided surface formed adjacent the mou~ting means of the supports 103. Additional parts of flat areas 109 can be formed along ...... .... ............ , .... ....... .................... ... . ,, , ,,, .,,, .. ,, .. , .. , ......... .. -su~p~rts 103 in case support of boærds 101 is needed at some point intermediate the ends of s~??orts 103.
In a preferred ærrange~ent supports 103 are disposed substæ~tially parallel ~o the longitudin 1 axis of an instrument housing 500 (sh~ in more detail in Fiss. 12a-12c). One or more circuit boards 101 are mounted to flat areas 109 of supports 103 --through æny ccnventional f2stening means, such æs the threaded fasteners 111 sh~wn in Figs. 2 ænd 3. Supports 103 and circuit boards 101 are dimensioned along their longer sides such that -lQ mounting means 107 project outward from the perimeter of circuit .~
boards 101. Circuit boards 101 and 102 are also dimensioned along their shorter sides to be less ~han the inside diameter of instrument housing 500 with circuit boards 102 being slightly narrower in width than ~oards 101..... The spacing between support ~-faces 109 determunes the spacing between facing boards 101 and is .:-chosen to prevent arcing fro~ occurring between the circuits etched on the facing boards. ~-Spacers 105 are sh~wn as short hollo~ internally threaded cylindrical studs which enable the mounting o~ one or more additional circ~it boards 102 to the first pair of circuit boards by means of threaded fasteners 106. Obviously, supports 103 of ~=
the elongated rod type can be substituted for the stu~ type E
spacers 105. Spacers 105 are merely shcwn ~to -~3nonstr~te that F
spaoe r means of other types can be ~!ced successfully in combination with supports 103.
A completea circuit board and support assembly, oomprising at least one circuit board 101 and a pair of supports 103 is then -mounted to a pair of mounting plates 113 and 115 as shown in Figs.
2 and 3. Mountins plates 113 and 115 have a substantially E:
circular shape and are dimensioned to fit within instrument E
housing 500O Mounting plates 113 and 115 may further include one F::
or more openings formed ~herein for accommodaiing wirins, such as t-:
a wiring harness 117 as shown in Fig. 3. Wiring harness 117 has E
been o~itted from the o.her drawing figures for the sake of clarity. Each of the mounting plates 113 and 115 further incl~des at least a pair of cp~nings adapted to receive mounting means 107 --:
of supports 103. --~ZiL~10g ' ` '' Mounting plates 113 a~ 115 are esse~bled to mounting means 107 of sup~orts 103 through respective op ninss 116 and 118 formed in pia.es 113 and 115. Preferably, mo~nting means 107 are threaded and mounting pla~Qs 113 and 115 are secured to the mounting mear~ by conven~io~al threa~ed fasteners 119.
In the embodim~nt shown in Figs. 2 and 3, mounting plates 113 and 115 are shcwn as separately mountable ccmponents. This enables o~e or more subst2ntially circular circuit boards 121 to --be mounted between rear mounting plate 113 and an instrument lQ housing end cap 123. Hcwever, in some instan oe s it may ke ~sired to mount the circuit board support assembly directly to end cap 123, as shown in ~ig. 4. In this case mounting means 107 of -supports 103 can D_ mcunted clrectly to an interior face 12; of end cap 1 3, or can be spaced apart therefrom by means of a pair of hol~ow intern~lly threaded spacers 127. A pair c~ threaded bolts 128 are used to secure end cap 123 and spacers 127 to supports 103. Thus, in the embodiment shown in Fig. 4, end cap 123 acts as one of the mounting plates for the circuit board ~-support assembly. ':
Likewise, mounting plate 115 can serve a dual purFose, namely ~:
as a base to which an analog~digital indicator assembly, such as ~--those shown in Fig. 1 and Figs. 6-10, can be mounted. Plate 115 can optionally be secured to housing 500 by m~ ~ of radially disposed threaded fasteners 124 (see Fig. 3). L
End cap 123 is of ccnventional design and is dimensioned such that faoe 125 fits se~urely within housing 500. End cap 123 in d udes a plurality of feed-through type electrical connectors 1~9 to which the wires o~ wiring harness 117 are oonnected.
Connectors 1~9 are surroun~ed by a socket shroud 131 formed as part of end ~ap 123. Connectors 1~9 and shroud 131 are of ccnventional design for use with plug-in or screw-on type wiring harnesses as is well knc~n in the aircraft instrumentation art.
End C'2p 123 is secured to housing 500 using conventional fastening means. For example, housing 500 can be internally threaded to --receive complementary threads formed ~n a mating portion of end cap 123 or a bayonet-type mounting arrangement can be used.
Alternatively end cap 123 is secured to housing 500 using radially --2~ Q9 dis~sed th.eadeà bolts or by means of soldering. If desired, a sasket-t~e seal, such as cn O-ring 133 can be provid~d around the periphery OL f aCe 125 .
~hile th~ mounting arrange~en. of Fig. 2 s~.-s a to,al of --S four rectangular circuit ~oards being mounted in a stacked fashio~, it is to be understood that fe~er or greater nu~bers of --circuit boards may be so arranged, as desired. For example, Figs.
3 a~d 5 show three circuit boards 101 and 102 mounted together.
Fig. 4 sh~s a pair of circuit boards 101 mounted in a spaced lQ apart fashion by supports 103, the su~ports in turn being attached -.
.o a mounting plate 115 and end cap 123, the end cap acting as a -mounting plate in this e~bodiment. -In Fig. 5 two circuit boards 101 and one circuit board 102 -are sh~wn mounted to su~ports 103 and spacers 105. The circuit r board and support asse~bly is then mounted to mounting plate 115 and end cap 1~3 as described above with respect to Figure 4. Due .. -to the modular arrangment a circ~lar circuit board 121 can be readily mounted between end cap 123 and the rectangular circuit ~
board mounting assenbly by means of hollow spacers 127 ana 130 E--through which threaded bolts 128 are run from end cap 123 to r~-intern~lly threaded m~ounting means 107. If desired, an elcnsated rod spacer 134 can be provided between mounting plate 115 znd end ~-cap 123 ~or a mounting plate 113) to provide even _~rther rigidity r to the circuit board and mounting plate assenbly.
Of course, other numbers and ccmbinatior~ d rectangular and/or circular circuit boards can be provided and would be obvious to one skilled in the art. In its mininum configuration ~-one circuit board 101 is mounted to a pair of suçports 103 by fasteners 111 and then mounted to mounting plates 113 and 11~, or F~'"
alternatively to end OEp 123 and mountins plate 115.
Several advantages flow from the above-described circuit E-board mounting arrangements. These arrangemer.'s help to isolate F:::
the rectangular circuit boards frcm vibration impinging on the ~-instrument housing as there is no direct contact or mechanical co~nection betwe~n the housing and the circuit boards. In additicn, the described arrangements are extremely flexible in that multiple circuit boards of both rectangular and circular .........................................................
Zl~109 ` I
-- 10 -- .
shape can be easily ~cunted tcsether in one com~act zssembly. In additicn, the descri3ed circuit ~oard mounting ~rranse~ents facilitate the use of elec.rical ccm~onen s and circuits, su^h as large scale integrated circuits aad r,icroprocessors, which ære --otnerwise too large to mc nt o~ a ccnventionAl circular circuit --board. As will be readily appreciated, a greater num~er of electrical components such as those denoted as 135, 137 and 139 in Figs. 2-5 can be mounted on a rectansular board as opposed to ::
ccnventional circular circuit boards (which of necessity can be no larger in diameter than the inside diameter of the instrument housing). ~y stacking rectangular circuit boards 101 and 102 only a minimum amount of interoonnecting wiring (such as flexible cakles or plug-in type terminals 141) need be used to connect ~
circuits on adjacent b~ards lOi and 102, as oompared to the large ~-amount of interconnecting wiring which is gener~lly needed in conventional stacked circular circuit board mouncing arrangements.
r'~
The described a~rrangements also reduce considerably the amount of labor involved in wiring and assembling the circuit boards into an r~'' integrated package for use in a cylindrical instrument housing.
Thus, the present invention affords not only a simple ~d vibration-resistant mounting for circuit boards but substan~ially reduce labor and material costs through greatly reduced E
requIrements for interconnecting wiring.
r A further advantage is that the modular ~ature of the prese~t r' invention enables all the circuit boards and associated F-.-electronics to be built as a subassembly separate and apart from ~-an analog and/~r digital instrument display (shown in Figs.
~--6-10). The flexibility inherent in these mounting arrangements ~-~
enables such circuitry to be tailored to an individual customer's -~
specifications for use with any type of display, whether analog, digital or a combination of both. The ab~ve-described --arrangements also allo~ cptimum use of the limited space available ~-in a cylindrical instru~ent housing while acoom~odating sophisticated electronic circuitry, all while providing a simple, easy to manufacture and rugged support for such electronics and -:~
associated display mechanisms.
2~ 9 ` I
3. Modul ar anal4q/digital instrunent display With reference ~io ~ig. 6, there is sn~n a modul~r Ga_klighted an210g/disital instrument aisplay ~sef ul with the 2~0ve-d~scribed cir~lit boærd mounting arr~rlgPmPnt. Display asse~bly 200 includes a base 201 (which .or exa~?le can be ,mounting plate 115 as shc~ in Figs. 2-5) to whicll an analog meter movement 203 is mounted in any convenient fashior.. ~leter move,~ent 203 is of conventional and well known d~sign and m2y for example cQnprise a ving coil mPcharlism of the D'Ars~val t~rpe. Meter , -movement 203 includes a rotatable sh ft 205 extending in a direction substantially parallsl to the longitudinal axis of an instr~nent housing 500 (as sh~t~n in ou~ine in Fig. 8). Meter shaft 205 includes æn articulated portion 207 formed at one end thereof t~ which an ~nalog dial p~inter 257 is mechanically E::-cor3nected. A bracket ænd spacer assembly 209 is mounted ,o the housing of meter move~nent 203 (or, alternatively, mounted to base 201). The meter housing includes a pair of ~ unting bosses 210. L
One probl~sn associated with asse~bling an analog meter mechani~n is the fact that the p~inter 257 generally must be attached to meter shaft 205 prior to mounting any other ccmponents F=
such as an 2na:Log dial, digital display or ~acklighting means.
This is because the meter mechanism must be balanced with the t--~pointer attached. Such a re~uirement prevent~s ,embly of the r--various analog cnponents in a straightforward manner. The foll~ing arrangement is intended to overccme this problem.
A circuit board 211, which for example is sub6tantially circular in shape and adapted to fit within the cylindrical b instrunen'c ~using, is mounted to bracket assernbly 209 as t described in more detail belc~. Circ~Lit board 211 includes an t=
opening 213 and slot 214 adapted to receive rotatable shaf t 205.
As sh~n more clearly in Fig. 7, circuit board 211 includes a ~F-plurality of electrical contacts cnprising plated through , -openings 215 fo~:med in circuit ~ard 211 to which the leads o~
digital display sockets 217 are attached in a conventional manner, such as by soldering. Sockets 217 are adapted to receive the leads of digital display readouts 219, which for example may be of the incandescent or light e~nitting diode types. -....... ........................................................................ ........ ....
- ........................................................................................................ ...... . . ....
zla~os -~ I
;
l~un'ed 'o circuit board 211 is light collecting plate 221.
Light collecting pla.e 221 is adapted to fi. wi~hin cylindric21 housing 500 and is forr-d from a subst~atially clear light collecting ma~erial su~h as that hr~ under th~ trademark PLEXIGL~S @. Light collec.ing plate 221 includes a first opening 223 adapted to receive digital display 219 and a second opening 225 and slot 226 adapted to receive the articulated portion 207 of ---meter shaft 205. The first o~ening 223 further includes a lip or -recess 227 formed therein for receiving a display filter 229.
lQ Disposed within opening 225 is one end of a light pipe 231 formed -- -frcm a light tran~nissive material such as that used for light -collecting plate 221 or of any one of a number of well-knc~n fiber optic materials ----Light collecting plate 221 further includes a recess 233 --fo~med in a portion thereof for receiving illumination means 235 and for enhancing the collection of light therefrom by light --:
collecting plate 221. Recess 233 also includes a portion adapted ---to receive the other end of light pipe 231 and to dispose it adjacent illunination means 235, as shc~wn in Fig. 8. Illumination means 235 cQ~prises, for exa~ple, a pai~ of incandescent lamps mounted to a circuit board 237. r,,_ Dial 245 is mounted to light collecting plate 221 ty threaded r~~
fasteners 247 and 248. Dial 245 is forme~ from a light L
transmissive or translucent material and includes one or more dial markings 249 proviaed therecn. Dial markings 249 are preferablyF::=
formed ~y screening selected areas of dial 245 and covering thek remainder with an opaqye c~ating such as flat black paint. ~-Alternatively, the dial m2rkings can oomprise opaque (dark) areas ormed on a transluoent dial. The dial and markings c2n also be forme as an integral part of one face of light oollecting plate 221.
Dial 245 includes an opening 251 formed therein which is adapted to expcse display 219 to view through filter 229 when the analog/digital instrument is assembled. Dial 245 also includes an opening 253 and slot 255 for accomodating the articulated end 207 :-....
'' of meter shaft 205. Dial pointer 257 can include an cp2que lisht reflective p~rtio~ 259 formed thereon (from whi.e paint, for ................................... ,,,,,,,.. ,...................... :: ::::.. :.-r~ ~LZ~L~lQ9 !
ex~mple) for selectively blocking or directing light e~ission from pointer 257 alc~g selected xrtions thereof. ;
The analo~Jdigital ins.r ment is asse~bled as folio~s. ~leter mechanism 203 is fasteneà to base 201 and brackets 209 are S attached to meter mechanis~ 203. Dial pointer 257 is attached -(such as by adhesive ~onding) to articulated end 207 of meter shaft 205. Spacer 239 is attached to circuit board 211 via threaded fastener 240. Circuit board 211 (to which sockets 217 have been previously soldered) is slip~ed over pointer 2;7 and :--lQ shaft 205 via slot 214 and seated on bracket spacers 209 and :--bosses 210 of meter mechanis~ 203. A pair of threaded studs 241 are used to secure circuit bo2rd 211 to bracket sp~cers 209.
Light pipe 231 is fitted into recess 233 provid~d in light collecting plate 221. The light pipe is retained in recess 233 by '-mounting lall~ circuit board 237 to light collecting plate 221 via -.
a pair of threaded fasteners 2430 ~-Light collecting plate 221 (with 12mp circuit bcard 237 and light pipe 231 assembled thereto) is slipp~d over pointer 257 and r~
meter shaft 205 through slot 226 so that articulated portion 207 t.
of shaft 205 is located just below light pipe 231 in opening 225 .~
of the light collecting plate (Fig. 8). The light ccllector ~-asse~bly is seated on the two mounting studs 241 and is fastened to meter housing bosses 210 via a pair G~ threaG ~ fasteners 244 F
which are passed through openings provided in the light oollecting E
plate, circult board 211 and spacers 242 (staked to circuit board E
237) . Mounting studs 241 are then tightened to fiDmly secure ~-circuit bo2rd 211 to bracket spacers 209.
Digital display readouts 219 are plugged into scckets 217 and polarizing filter 229 (if a self-illuminated digital display is 'F~-used) is fitted into recess 227 provided in light oollecting plate ~:
221.
Dial 245 is fitted over pointer 257 through opening 251 and '--over articulated portion 207 of meter shaft 205 via slot 255 -:-provided in dial 24s (similar to slok 226 provided in light collecting plate 221) so that the artlculated portion of the meter --shaft is disposed in dial cpening 253 (Fig. 8). In cases where --pointer 257 is too large to fit through opening 251, slot 255 can ~-~ 121~ 9 ~ !
i be, brought all the way out to the circu~nfere!lce of dial 245 (see Fig. 9).
~o threaded fas.~ ers 247 are placed thro~.2gh o?enir,ss provided at a2proximately ~he 8 o'clock and .~ o'clock positions of dial 245 and ligh, colle~ins p' ate 221 and fas.ened to mounting studs 241. Threaded fastener 248 is passed through an opening provided at a~?ro~:im.2tely the 12 o'clock E~osition of dial 245 and fastened to a similar threaded opening pro~ided in light collecting plate 221. Threaded faste, er 250 is passed through lQ openings provided at a?proximately the 6 o'clock position of dial 245 and a lc~e~ portion of filter 229 and is fastened to spacer 239.
Once the analog/digital instrunent asse~nbly is cnpleted it can be readily attach~d to the circuit board mounting arrangement described earlier and inserted into cylindrical housing 500 as shc~n in Figs. 8 and 12b. A clear wind~ 505 is disposed between a retaining ring 503 which is fitted over one end of cylindrical housing 500. Ihe digital display circuitry and analog meter movement are readily connected to excernal signals or to signal 2 0 processing/conditioning circuitry (such as that described ab~ve with respect to the circuit board mounting arrange~nent) in any canventional f shion, such as thrcugh connectors 129 of end cap 1?3.
~t will be al~preciated that the above-described arrangement ~nables a baclclighted analog/digital display, including an ill uminated dial pointer, to be readily ass~nbled without interference occurring between the digital display ccmFonents and the analog mechanism and pointer . Bac clishting of dial 245 is provided by the light frcm ill unination means 235 which is collected and transmitted through light collecting plate 221. The light fran illum~nation means 235 is also transmitted to dial pointer 257 via light pipe 231.
If display 219 is o the self-il1uninated type no edge-lighting is needed. Indeed, edge-lighting of such a self-ill ~ninated display ~uld re~uoe display contrast by washing out the illuminated digits of display 219. To prevent this fr~n happening, and to enhanoe display contrast for such self-.......................................................................... _ .... . = . .......... . ... ... .
2~09 illu~ina.ed displays, filter 229 is of the polarizing type which acts to reduce the effect 0c anbient light on the ex2osed face of digital display 219. In cddition, the edge of recess 233 ls coated with 2n opaque m3.Qri21, su~h as black Faint, to prevent lisht transnitted througn 11sht collecting plate 221 from reaching the exposed faoe of the digital display. Of course, if a non-self-illu~inated display, such 2s a liquid crystal display, is used and it is desired to edge light su~h a display, the edge of recess 233 can be left clear and polarizing filter 229 can be o~itted.
The d~scribed analog/aigital display arrangement thus enables a simple yet versatile ins~rument to be built all in one compac~ - -unit which can be fitted into a cylindrical instrument housing. ~-As the various c~nponents are modular, the digital and an210g portions of the displays can be assembled (or disasse~bled for -~-repair) without interference with one another. This greatly reduces the time and labor involved in manufacturing such displays and th~s results in a low cost, yet rugged analog~digital display.
Fig. 9 sh~ws an alternative embcdiment of an analog/digital display 300. ~isplay 300 is in many respects similar to that ~
2Q shcwn in Fig. 6 and similar o~nponents are denoted using similar ~-reference nunerals. ~:
In Fig. 9 a non-self-illuninated display 301 is shown, such as a liquid crystal display. Such displays may b- c the leadless F
type, as sbown, or may include leads or pins for mounting to a s x ket ox directly to a circuit board such as previously described E
with respect to Fig. 7. If 2 leadless unilluminated display such .-as 301 is used, some means for connecting contact pads fonmed on the display with etched tenninals 215 foxmed on the surface of circuit board 211 must be provid~d. Such contact means can take ~-=
many forms. Hcwever, in the preferred emb~diment such oontact ~::
means take the form of tw~ contact strips 303 of elastomeric dielectric materi.l in which are embedded (or formed on a surface ,F'',':
thereof) a plurality of spaced apart conductive portions. Such types of elastomeric o~ntact strips are well kncwn and include thcse sold unde~ the trade nane ZEBRA~
As contact strips 303 are scmewhat flexible scme means for --.
supporting them must be provided be.ween display 301 and terminals f~ lZ~ 9 - I
!
215 of circuit ~oard,211. To this end, a guide 305 having two transverse slots 307 fo~d therein is mounted to circuit board 211 b~ me~ns o' fasteners 309. I~ount 311 for illumination means 235 also inoludes a pair of transverse slots 313 adapted to receive and suide portio~s o' con.ac, strips 303.
Light ool1ecting plate 315 is some~hat similar in arra~gem~t to collecting plate 221 (Fig. 5) and incluaes a recess 317 and a pai~r of transverse slots 318 (aligned with slots 313 of board 311) which are adap.ed to receive display 301 and contact stri~s 303, 1~ respectively, and a second opening 319 adapted to receive light pipe 231 and meter shaft 20;.
Analog/digital display 300 is asse~bled as follows. Analog meter mechanis~ 203 is unted to base 201 and single spacer bracket asse~bly 329 is fastened to the housing of mechanism 203.
-15Circuit board 211 is slip~ed over shaft 205 through radial slot -,' 214 and is secuLed to bosses 210 and bracket spacer 329 by means --of three threaded mounting studs 241. Contact strips guide 305 is ---mounted to circuit board 211 via a pair of ,hreaded fasteners 309 which fit into threaded bushings 310 mounted to circuit board 211.
20Light pipe 231 is plaoed in recess 316 (si~ilar to that shown ~-in Fig. 8) formed in light collec.ing plate 315 with one end ~,-disposed in oFening 319 of plate 315. L2~p mount 311 (to which rr lamps 23S have been previously attached) is fi,'~d to the rear ~=
face of light collecting plate 315 with transverse slots 313 of mount 311 aligned with slots 318 of plate 315. The light t 25col1ecting plate and lamp mount are slipped over shaft 205 and E
pointer 257 (which has been previously attached to shaft 205 in order to allow the meter mechanism to be balanced) via radial F
slots 321 and 323 formed in plate 315 an~ lamp mount 311, respectively, ~r 30Light collecting plate 315, light pipe 231 and lanp mount 311 ~,-are secured to the upper pair of mounting studs 241 (previously t`
secured to b~sses 210) by means of threaded fasteners 329 which t fit into recessed opemngs formed in light collecting plate 315.
Contact strips 303 are inserted through slots 318, 313 and ~'-35307 of the light collecting plate, lamp mount and contac, strips guid~, respectively, until they are in oontact with etched '~' ~21C~`~109 ~ !
I
contacts 215 formed on circuit board 211. Liquid crystal display 301 is plaoe d into recess 317 of light oollecting plate 315 until its leadless con~acts ab-t the edges of co~tac. s.rips 303.
Dial 245 is sli~ed over cointer 257 and shaft 205 in a similar fashion as described ~ith respect to Fig. 8. Dial 245 is mounted to light collectlns plate 31~ by means of three threaded --fasteners 325 and one threaded fastener 327. F~steners 325 are threaded into dial 2g5 and light oollecting pla,e 315 at approximately the 8 o'clock, 12 o'clock and ~ o'clock positions, while fastener 327 is threaded through dial plate 245, light collecting plate 315 and lamp mount 311 2t approxim2tely the 6 o'clock position, and is secured to mou~tins st~ 2Al. As opening 251 of dial 245 is dimensioned slightly smaller than the outer periphery of display 301, the display is securely cla~ped into contact with contact s.rips 303 by àial 245.
With the above-describ~d arrange~ent a non-self-illuminated digital display, such as 301, is edge-lighted by the light frcm illumination means 235 that is col1ected and transmitted through light collecting plate 315. In addition, lisht collecting plate 315 acts to backlight dial 245, and dial pointer 253 is - --illuminated by light from illumination means 235 which is -r transmitted through via light pipe 231 as described above with respect to Figs. 6-8. In addition, the _ov~-described arrangement readily accommod2tes digital displa~s of the leadless type (whether self-illuninated or not) in a ccmpact, rugged and easy to assemble package.
Fig. 10 shows yet another technique for mounting leadless digital displays in an analog/digital instrunent, and further shows an alternative technique for attaching a dial pointer to an 't'.
analog meter shaft (Fig. 11). Parts and ccmponents in this emkodiment which are commcn to those in the aforementioned t embodlments are denoted using identical reference numerals. r''-Threaded mounting studs 409 are used to nu~nt circuit board ~-211 to spacer 423 and bosses 425 af meter movement 203, which in turn is mounted to b~se 201. Circuit board 211 can be connected :-to external signals throush any conventicnal means, such as by means of a wiring harness 421 (sh~wn Fartially in ~ig. 10).
~ ~L21~1Q9 i Le2`1ess display. 301 is ~.~ounted to etched te~ninals Z15 formed on circuit bo2rd 211 via elastomer-type contact strips 303. Instead of slotted cuiae 305 and la~p mount 311 (Fig. 9) a --spacer 401 is dispcsei set~n circuit board 211 and display 301.
A display housing 403, having an oæ ning 40; formea therein for -exposing display 301 .o vie~, is seated against spacer 401 and fastened o circuit board 211 by means of fasteners 407. Display housing 403 acts to cla~.~ disital display 301 firrly against contact strips 303, thereby causing contact strips 303 to be .. -lQ securely urged into contact with contact pads formed on display 301 and etched contacts 21; of circuit board 211. A pair of .-gaskets 407 are also provided between either end of display 301 -:
and a surface of spacer 401. The rear of display 301 dbes not contact spacer 401. -After digital display 301 is assembled to circuit board 211, dial 24~ is secured to studs 409 by a pair a threa.~ed fasteners -411. Nanrilluminated pointer 413, which includes a threaded portion 415 along shaft 416, is screwed into a .~."plementary .. -threaded bu.shing 417 disposed in rotatable meter sl~aft 419 of meter mechanism 203 as is more f~-lly described belcw with respect ,t.
to Fig. 11.
In the e~cdiment shown in Fig. 10, no illumination means for ~=
the digital display or backlighting means for the ~ial and pointer l_ is provided. ~.owever, it will be understo~d that such illumlnation and backlighting means c~uld be readily incorporated into this em~odiment. For example, display housing 403 could be fonmed fr.om a light tsansmissive and collecting ~aterial and E
illuTination means (such as 235 shc~n in Fig. 9) could be disposed r~' adjacent thereto to edge-light display 301. Alternatively, a ~.
light collecting plate such as 221 (Fig. 6) or 315 (Fig. 9) could ~:
be incorporated to provide edge-lighting of display 301 and ~
bac~lighting of dial 245. If an illuminated pointer is desired, .-pointer 413 could be ~eplacec. with an i11uminat.~d pointer such as Z57 (Figs. 6 or 9) and light pipe 231.
The display mounting arrangement of Fig. 10 adva.ntageously enables a leadless digital display and associated contact strips to be securely clamped into contact witn terminals ronmed on a :
:121~`~Q9 .--', circuit board. As is apparent, the described arrange~ent enables the dis~lay to be moun.es without interference with the analog meter mechanis~ or me.er shaft. ~he screw on Fointer simplifies assembly where illuminatio~ of the poi~ter is not needed.
~Sore par,icularly, the use c~ screw on pointer ellminates the need for slots or cut-outs in the dial which may detract from the appearan oe of the dial. Yihile the construction of a screw-on pointer would appear to be a straightforward proposition, several problems arise. First, the meter shaft 419 generally is formed from extremely thin-walled hollcw tubing (usu lly of a light-weight material such as a soft-grade of aluminum) which is not ---easily internally threaded due to its thin~ess. Thus, if more ~
than a slight anount of force is applied to shaft 419 it will .-likely bend or distort and des',roy its usefulness as a meter L-:
shaft. Second, in attaching pointer 413 to meter shaft 419 it w~uld ~e desirable if the pointer could be lc,cked in a desired angular position with respect to meter shaft 419 and dial 245.
Finally, the distance from the pointer to the face of the dial ~
should be adjustahle to allow for slight variations in tolerances E
(such as ~hickness) of the various components. L:--To this end, the screw-cn pointer shown in the detail cross-secticn of Fig. 11 is constructed and assembled as follows.
Bushins 417 is internally threaded and includ a collar 418 F
formed on one end thereof. Bushing 417 is fitted into one end of ~-meter shaft 419 with the collar abutting the end of the meter c shaft. Bushing 417 can be formed from a thin-walled, yet easily ~t machinable material (such as a machinable grade cf aluminum) and serves to stiffen the end of meter shaft Al 9 into which it is inserted without adding substanti~l~y to the weight or inertia of t-shaft 419. Bushing 417 is held within meter shaft 419 by a dab of adhesive which is ap~lied to the outer surface of the bushing -,-prior to its insertion into the meter shaft.
Pointer 413 includes an opening 414 enabling the pointer to be sliFped over pointer shaft 415 until it is seated against the -::
underside of shaft head 429 wnich is c~ a di~neter larger than the shank of pointer shaft 415 and pointer oFening 414. Pointer 413 .
is secured to shaft 415 and head 429 by conventional fastening .::
.. , - -- .. ............................................................................... ... ..... . .. . .
121(~ )9 me~ns, such as adhesive bc~ding. Lcc~nut 427 is then threaoed over tl~e threaded portion o~ x inter shaft 415.
Th~ digital dis?lay ænd dial are assem~led together as described with respect to ~ig. 10. The ~hreaded portion of pointer shaft 415 is passed thro~lgh opening 253 of dial 245 ænd threaded into bushing 417 until pointer 413 is at the desired distance frcm dial 245 and at a desired angular position with :,, respsct to the dial. The pointer is then secured in position to ,' meter shaft 419 by turning locknut 427 ~by means of a pair of :
1~ tweezers, for ex3mple) until it contacts collar 418 of bushing 417. If desired, the locknut can be permanently secured by --ap?lying a dab d adhesive at the point where it and p~inter shaft 415 contact. -' As is aFparent, the oescribed screw-on p~inter enables the angular position and distan oe of the pointer with respect to the diaL to be readily adjusted. The threaded bushing inserted into the meter receives the threaded pointer shaft and acts to stiffen '-''' the walls of the meter shaft to prevent bending or distortion thereof when the pointer is threaded to the meter shaft. ',', As mentioned earlier, the circuit b~ard arrange~ent of Figs. ,--2-5 and an log/digital display arrangements of Figs. 6-10 are -~
designed to fit within th~ confines of a standard (e.gO 2 inch) dia~eter instrunent housing 500 as shown in .gs. 12a-c. A t typical anaLog/digital instrument faoe is show,n in Fig. 12a. --Analog/digital instrument 200 and circuit board mount 100 are r-sh~wn disposed within cylindrical housing 500 in the cross~
sectional view of Fig. 12b. Fig. 12c shcws a rear view of housing ~-, 500 with end cap 123 secured in plaoe . ~-As briefly mentioned earlier, circuit boards 101 and 102 can oontain electronic circuits and ~ ponents for driving the digital ,t~, displays and performing scaling and signal processing functions for the analog meter mKve~ent. An example of one type of ,-ccnventional circuitry which can be used with the various --embodiments of the present invention is shown in block diagr~
form in Fig. 13. '' The foregoing description is not intended to ~e limitive or ', exhaustive but rather illustrative of the invention wnich is '-,',',-defined ~y the ~aDpended claLms. -'' ......................................................... ...................................................................... .
. .
Claims (11)
1. A modular analog/digital instrument display for use in a cylindrical housing including:
a base adapted to fit within said housing;
an analog meter movement adapted to fit within said housing and mounted to said base, said meter movement including a rotatable shaft having a portion thereof extending in a direction substantially parallel to the longitudinal axis of said housing;
a circuit board adapted to fit within said housing and mounted in a spaced-apart relationship to said meter movement, said circuit board including electrical contacts formed on at least a portion thereof, said circuit board further having an opening formed therein for receiving said meter movement shaft;
a digital display;
means for mounting said digital display to said circuit board including means for electrically connecting electrical contacts of said digital display with said contracts of said circuit board, an analog dial adapted to fit within said housing and mounted to said circuit board, said dial including a first opening for receiving said meter movement shaft and a second opening for exposing said digital display to view; and a dial pointer mounted to the end of said meter movement shaft extending through said dial, said dial pointer being arranged adjacent to a face of said dial.
a base adapted to fit within said housing;
an analog meter movement adapted to fit within said housing and mounted to said base, said meter movement including a rotatable shaft having a portion thereof extending in a direction substantially parallel to the longitudinal axis of said housing;
a circuit board adapted to fit within said housing and mounted in a spaced-apart relationship to said meter movement, said circuit board including electrical contacts formed on at least a portion thereof, said circuit board further having an opening formed therein for receiving said meter movement shaft;
a digital display;
means for mounting said digital display to said circuit board including means for electrically connecting electrical contacts of said digital display with said contracts of said circuit board, an analog dial adapted to fit within said housing and mounted to said circuit board, said dial including a first opening for receiving said meter movement shaft and a second opening for exposing said digital display to view; and a dial pointer mounted to the end of said meter movement shaft extending through said dial, said dial pointer being arranged adjacent to a face of said dial.
2. A modular analog/digital instrument display as claimed in claim 1 and wherein said mounting means further comprises spacer means disposed between said circuit board and said digital display, electrically conductive means disposed between said digital display and said circuit board for connecting said electrical contacts of said digital display with said electrical contacts of said circuit board, and means for clamping said digital display, electrically conductive means and spacer means to said circuit board.
3. The instrument display of claim 2 characterized in that said meter shaft includes an internally threaded bushing and said dial pointer includes a complementary threaded portion and lock-nut for attaching said pointer to said threaded bushing provided in said meter shaft.
4. The instrument display of claim 3 characterized in that said digital display includes at least one row of electrical contacts formed thereon, said circuit board includes at least one row of electrical contacts formed thereon and disposed substantially opposite said digital display contacts, and wherein said electrically conductive means comprises at least one strip of dielectric material having electrically conductive portions provided thereon, said electrically conductive portions being spaced apart and arranged to electrically connect said at least one row of digital display contacts with said at least one row of circuit board contacts when said digital display is assembled to said circuit board.
5. The instrument display of claim 4 characterized in that said electrically conductive means comprises as least a pair of strips of elastomeric dielectric material having electrically conductive regions formed therein, said elastomeric strips and said spacer means being dimensioned such that when said digital display, elastomeric strips and spacer means are fastened to said circuit board by said clamping means said elastomeric strips are slightly compressed whereby said digital display contacts and said circuit board contacts are positively electrically connected through said conductive regions of said elastomeric strips.
6. The instrument display of claim 2 characterized in that said spacer means includes at least one guide means adapted to fit within said housing and displaced between said circuit board and said digital display, said means including at least one transverse slot formed therein for receiving and guiding said electrically conductive means between said display contacts and said circuit board contacts, and said clamping means clamps said digital display, electrically conductive means and spacer means to said circuit board, said clamping means comprising said analog dial.
7. The instrument display of claim 6 characterized in that said meter shaft includes an internally threaded bushing and said dial pointer includes a complementary threaded portion and lock-nut for attaching said pointer to said threaded bushing provided in said meter shaft.
8. The instrument display of claim or 7 characterized in that said digital display includes at least one row of electrical contacts formed thereon, said circuit board includes at least one row of electrical contacts formed thereon and disposed substantially opposite said digital display contacts, and wherein said electrically conductive means comprises at least one strip of dielectric material having electrically conductive portions provided thereon said electrically portions being spaced apart and arranged to electrically connect said at least one row of digital display contacts with said at least one row of circuit board contacts when said digital display is assembled to said circuit board.
9. The instrument display of claim 8 characterized in that said electrically conductive means comprises at least a pair of strips of elastomeric dielectric material having electrically conductive regions formed therein, said elastomeric strips and said guide and spacer means being dimensioned such that when said digital display, elastomeric strips and guide and spacer means are fastened to said circuit board by said clamping means said elastomeric strips are slightly compressed whereby said digital display contacts and said circuit board contacts are positively electrically connected through said conductive regions of said elastomeric strips.
10. An instrument display as claimed in any one of claims 1, 2 or 3 and including means for backlighting said dial.
11. An instrument display a claimed in any one of claims 1, 2 or 3 and including means for illuminating said digital display.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US26285081A | 1981-05-12 | 1981-05-12 | |
| US262,848 | 1981-05-12 | ||
| US06/262,848 US4404522A (en) | 1981-05-12 | 1981-05-12 | Display connection scheme for modular analog/digital instrument |
| US262,850 | 1981-05-12 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1210109A true CA1210109A (en) | 1986-08-19 |
Family
ID=26949496
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000402727A Expired CA1210109A (en) | 1981-05-12 | 1982-05-11 | Electrical measuring instrument |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1210109A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109703364A (en) * | 2018-11-30 | 2019-05-03 | 惠州市德赛西威汽车电子股份有限公司 | A kind of fit structure and mode of gauge pointer and motor |
-
1982
- 1982-05-11 CA CA000402727A patent/CA1210109A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109703364A (en) * | 2018-11-30 | 2019-05-03 | 惠州市德赛西威汽车电子股份有限公司 | A kind of fit structure and mode of gauge pointer and motor |
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