Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
~28702
M~a~uring Instrument
The pre3ent invention relates to an opto-elec~ronic
mea~urin~ inetrument for detexmining the relative position o~ an
object in respect to a horizontal plane, with ~n at lea~t
partially transparent measuring chamber in which two media which
cannot be mixed of different denYity are contained, wherein one of
the media is at least partially tran~parent translucent and at
lea~t the other is a fluid medium, and wherein the relative
position is determined on the ba~i~ of the position of the at
lea~t partially tranjparent ~edium in the mea~uring chamber, with
a light sour~e ~nd a light-jen~itive sensor, onto which the light
transmitted ~y the light qource through the at lea3t partially
transparent medium is projected ~nd the projection i~ u~ed to
determine the relative po~ition. The invention fu~thermor~
relates to a method for determining the relative po~ition of an
o~ject in re~pect to a hori~ontal plane by means of a measuring
in~trumen~. Finally, the invention relates to a use of the
mea~u~ing in~trument.
In~t~ume~ts for determining the relative posi~ion or the
angle of objects in respec~ to the horizontal plane or the
perpendicular are known. Probably the best known instrument i~
the so-called water level or bubble level, in which an air bub~le
iq mai~tained in a liq~id inside a curved tube clo~ed at both ends
and wherein thi~ bubble is located exactly at the zenith o~ the
tube curve over the entire me~suring range.
In the course of improving the mea~uring accuracy, this
rela~ively rough-indicating device ~as refined in that other gases
were u3ed in place of air, or even that an extremely small amount
of a second liquid of lower de~sit~, which cannot be mixed with
the fir~t liguid and in addition i3 transparent, i~ al~o enclosed
in the fir~t li~uid and the first liquid i3 colored or opaque.
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It i~ possible by an appropriate optimization of the two
non-mixable fluid media to create minute bubbles for allowing an
extremely clo~e measurement by mean~ of a principle corresponding
to the conventional water level In this way special oils, liquid
silicons, noble gases, etc. are used today ~or a measuring
i~strument operating in accordance with the described medium. In
spite of this the problem of an accurate optical detection
remain~, because definite limit~ are set for the accuracy of
reading off, e~en with the mo~ minute hubbles, while the ease of
reading is poor, i.e. the visual detection of the small bubbles i~
hardly possible.
An opto-electronic inclination detection is known from the
reference l~TECHNISC~ES M~SSEN" ~Technical Me~suring], ~ol.5a, No.
3, March 1~91, M~nchen D~, pp 101 to 105, XP 224809 and from GB
2,232,762 A, FR 2,368,6g4 A and EP 168 150 A1. Kowever, these
known de~ices onl~ permit angular mea~urements within a narrow
angular range of approximate~y + 20. A 360 mea~urement is not
possible with the~e de~ice~.
A further electronic inclinometer is ~nown ~rom DE 38 36
794 A1, which has a tube in the shape of an arc of a circle in
which an air bubble i~ en~rained. Beams are directed radially
from the inside to the outside through this tub~. A sensor is
p~ovided at the zenith which, after an i~clination of the device,
iQ ~eturned to the ze~ith by an adju~tme~t device. The angle of
inclination is calculated by means of the adjustment device. This
device is relatively cumbersome and ~low.
It is ~he object of the invention to provid~ a device which
permits a mea~urement over an angle range of 360.
This object is attained in accordance with ~he invention in
that the light ~ource, the measuring chamber and the light
~ensitive sen~or are dijpos~d behind each other on a horizontal
axis, that the light ~ource i~ di~poQed on one side of the cha~ber
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and the light-~en~itive ~en~or on the other side of the measuring
chamber, that the mea~uring ~hamber is embodied as a circular tube
or a hollow body in the ~hape of a circular disk and that the
enti~e projection o~ the mea~uring chamber 19 placed on ~he li~ht-
sensi~i~e ~ensor.
~ n opti~al measuring in~trument i~ propo~ed which
e~enti~ly operate~ in accordance with the known principle of the
water level determining the relative po~ition of an obje¢t in
reqpe~t to a horizontal plane or the perpendicular. The measuring
in~trument proposed by the invention comprises an at least
partiall~ transparent measuring chamber ~ontaining t~o media of
different density which cannot be mixed, wherein one of the media
iB a~ least partially tran~parent o~ translucent and at least the
other i9 a fluid medium, and wherein t~e relative position or the
angular po~ition of the object in re~pect to the horizontal plane
i~ determined on the basig of the poeition of ~he at least
partiall~ transparent or t~an~lucent medium in the mea~uring
chamber. A light source is disp~ed on one side of the measurlng
chamber, i.e. one side of the me~uring ~hamber is illuminated by
the light BoUrce ~ and an optical measuring cell or a light-
sensitive, ~lat sensor i~ di~posed on the opposite side of the
measuring cham~er, i.e. the ~ide oppo~ite the illumination, onto
which the lig~t transmitted by the li~ht source through the at
least partially transparent o~ translucent medium is projected,
whe~ein the projection iB u~ed for determining the rel~tive
position of the object in respect to the horizontal plane. In the -
pro~ss it i~ also pos~ible for the light to be polarized while :
mo~ing through the medium.
Exempla~y embodimen~ will be subsequently deecribed
wherein the light can also be polarized, jo that ~ special mention
o~ this in every example can be omitted. It is furthermore
pointed out that the projection o~ the ligh~ can be performed by
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u~ing lenses or other optical means, such as filters, pri~ms, of
the like, or directly, i.e. without len~es and the like .
Preferably both media are fluid media and one of the media
is an opaque medium or imperviou~ to light, wherein the two media
are enclosed in a tran3parent hollow body, preferably of glas~
At lea~t one of the media here must be liquid, while the
other medium can al~o be liquid or gaseous or solid.
Depending on whether the at least partially tran~parent or
translucent medium has a higher or lower density than the other
medium, the former i~ di~poRed at the zenith or the side opposite
the zenith of the hollo~ body or the measuring chamber.
Depending on the relative position to be measured or of the
angle enclosed by t~e objeot and the horizontal plane, the
measuring chamber or hollow body can be embodied in di~ferent
wa~, preferably with a con~tant cross section tran~ver~ely to the
tube or the di~k.
The optical mea~rin~ ~ell or the light-sensitive flat
~en~or di~posed for detecting the projection can be, fox example,
a ~o-called PSD detector (position-sensitive device) or a so-
c~lled CCD (charge-coupled device). However, any optical or
light-~ensitive mea~u~in~ cell~ are suitable for thiQ.
For determining the relative position of an objeet in
re~pect to the horizontal plane by means of the above described
measuring i~6trument in accordance ~ith the invention, light from
a light ~ouroe, which i~ disposed on one side of the measuring
chamber, is transmitted through the mea~uring chamber and through
the a~ least partially transparent or translucent fluid medium and
is projected onto the optical mea~uring cell or the light-
sensitive flat sensor di~posed on the ~ide oppo~ite the other
~ide, wherein ~rom the po~ition of the projection on the cell or
on the sensor the relati~e po~ition of the object or the substrate
i~ determined.
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The relative po~itio~ ox the an~ul~r position o~ ~he o~ject
i~ dete.rmined by means of the po~ition of the center of the
transmitted light spot or the ~hadow of the projee~ion onto the
position-~en~itive light sensor and is displayed by ~eans of
suitable eval~ation and indicator element~.
The m~a~uring instruments defined by the invention or the
method for operating them are particularly ~ited for use in an
electronic water level. Further u~e~ are found in electronic
leveling in~ruments, level meter~, ~ompens~tors and devices for
the ele~tronic detection of the acceleration of ~n object. Use of
the measuring in~t~u~ents in accordance with the invention are
fea~ured in claim~ 10 t~ 13, among others.
The in~ention ~ill be explained below in detail by wa~ of
example by meang of preferred devices in accordance with
in~ention. Shown in the process are in.
Figs . 1 and 2, a longitudinal and cro~s ~ection of a first
variant embodiment of a measuring in~txum~nt of the invention
~chematically I :
Fig~. 3 and 4, a furthe~ variant embodi~ent of the
invention in lo~gitudinal and croQs ~ection. -
A mea~uring chamber 1 is represen~ed in Fig. 1 in
longitudinal ~nd cro~s section, containing an annularly or similar
embodied hollow body 3. The cixcularly bent hollow body 3
contain~ a viscous translucent or opaque liquid 7 with an air
bubble 8 or a bubble of a transparent or at lea~t partially
transparent medium. As can be clearly seen i~ Fig. 2, a light
source 13 iB dispo~ed on one side o~ the hollow body 3. The light
beams 15 emi~ted by this light source 13 illuminate the hollow
body 3 on one side. Since the tube i~ embodied to be gla~s-like,
a part of the light in the axea of the air bubble 8 i~ transmitted
through the tube and the light beams 17 which pass through
corre~pondingly ~re projected onto a ~ensor 21 dispo~ed on the
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other ~ide of the tube. In the proc~ss a light spot or shadow ~3
ia generated on the ligh~- en~itive sensor 21.
I~ now the object on which the optical measuring chamber 1
of the invention i~ disposed is inclined in respect to the
hori~ontal plane (Fig. 1), the air bubble ~ or the bubble of the
transparent or partially tran~parent medium movee inside the
hollow body 3. However, the light spot or shadow 23 aleo moves on
the light-sensitive sensor 21, by means of which the different
relative position (A), ~hown in dashed lines, of the object can be
opti~ally detected. The detection of the light spot 23 and the
evaluation of ~he pojition of thi~ light spot 23 on the light-
sen~iti~e sensor 21 takes place in a~cordance with techniques
known per se, in that the 3en~0r 21 can ~e a so-called poeition-
sensi~ive detector PSD (position ~en~itive devi~e), for example.
The detection of the light spot or the pro~ection is particularly
~imple in this ca~e, becau~e the center of the light spot 23 is :
always automatically detected, because of which additional
calculating operation~ can be omit~ed. Howe~er, it i~ al~o
po~ible to selec~ a matrix-like detector CCD (charge- ~oupled
device) in the $o~m of silicon cell~ connection with which it
i~ first necessary to cal¢ulate the center of the light spot
projected onto the matrix.
In place of a liquid or air, it i~ al~o possible to select
two different liquid6 forming two separate pha~es and having
di~ferent densitie~. It is al~o po~sible to select a noble gas,
such aQ helium, in place of air. Since the optimal selection of
the liquid~ or of a gas and a liquid rep~e~ent commonly known
technologies, no further reference i~ made to it here.
Tt is of course also possible to di~po~e a solid body of
low density in a liquid. It is alqo possible to enclose a small
amount o~ a colored or opaque liquid in a tran~paren~ liquid, so
that reversely to what was described above, a dark spot in pla~e
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of a light spot is generated on the light-~ensitive sensor or
detector. However, the ba~io prineiple remains the same here
In Figs. 3 and 4 the mea~uri~g chamber 1 comprises a disk-
like circular hollow body 3 with an exterior wall 4. In this ~ase
the circular disk ha~ a con~tant cro~s seetion tran~v~rsely to the
disk. Again, the hollow body 3 contains a liquid 7 which is
opaque or impexvious ~o light and an air bubble ~ or a bubble of a
transparent or parti~lly transparent medium.
The mode of operation of th~ measuring in4trument in
accordance with Fig~. 3 and 4 is analogous to that of the
previously described mea~uring in~truments.
The advantage of the ~wo measuring instrument~ resides in
~hat the relative posi~ion or angular devia~ion o~ an object ca~ I
be measured or detected over a complete turn of a circle, i, e.
over 360
The accuracy of measurement can be cho~en to be different
by means of the selection of the radius R. With a very large
radius R the accuracy of m~a~urement is of course greater than
with a cmall radius R. However, the size of the measuring
instxu~ent in accordance wi~h the invention increase~ when a
greater ~adiu~ R i9 selected, because of which the u~e might
po~ible become ~ue~tiona~le.
The variant embodiments of the invention are used for
explaining and botter understanding the inven~ion and can of
course be modified, varied or changed in any desired way. Thu~ it
is po~ible to ~elect any combinations of two media which cannot
be mixed, wherein at least one of the media, which i~ virtu~lly
used a~ the carrier medium, must be fluid, i.e. liquid. The other
mediu~ for the indication or detection of the relative po~ition of
an object in respect to the horizontal can be either solid, liquid
or gaseous. The de~ign of the measuring chamber 1 itself can also
be ~elected in an~ way, basically all tran~parent hollow bodie~ 3
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are i~uitable. The seleeted light source 13 can also be either
vlslble light, infrared or UV, where in the latter cases the two
media in the hollow body ~ mu~t of course be selected such that
the detection of the emitted light on an appropriately sensitive
detector material i~ po~ible.
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