Note: Descriptions are shown in the official language in which they were submitted.
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MICROPHONE EQUIPPED WITH A RANGE FINDER
The present invention relates to a microphone that comprises a microphone
housing, an acoustoelectric transducer in a forward part of the housing for
receiv-
ing sound from a sound emitter, as well as equipment for transferring sound-
repre-
s senting signals from the transducer, out from the microphone to external
sound
signal processing equipment.
Microphones, and iri particular song microphones, often have a problem in
the fact that the distance from the microphone to the sound emitter, for
instance
the mouth of an artist, influences the sound resulting from the microphone
record-
ing. Microphones have various types of directional characteristics and various
types of distance response, and often a manufacturer will undertake
optimalization
with regard to certain parameters, when making a microphone. Hence, one
special
microphone will for example be intended to be used at a very close range,
while
some other microphone may be manufactured to pick up sound from a larger dis-
~s tance. A microphone that has been optimised for one certain~type of use,
may pro-
vide a poor result when the use deviates somewhat from the originally intended
use, and the result rnay be exaggerated S sounds, incorrect frequency response
etc.
US-A-4,586,195 discloses a microphone range finder system in which re-
zo produced speech is improved by compensating for the position of-a speaker
rela-
tive toga microphone system that includes a microphone and separate range
finder
or range finders. This system is intended for measuring distances across
tables or
across small or large rooms, and the microphone and range finder or range
finders ,
are separate units. The system is suitable for improvirig conditions for
instance
zs when a speaker walks away from a stationary microphone, however not in a
situa-
tion where a speaker or singer holds the microphone in hislher hands.
Thus, there still remains a need of a microphone of a more flexible type, i.e.
a microphone that can easily be adjusted regarding optimalization parameters
for
varying distances to a nearby sound emitter. The present invention aims at
solving
30 ~ this problem, and in accordance with the invention there is provided a
microphone
such as stated in the introduction, and which is characterized in that it is
equipped
with an element for measuring the distance to the sound emitter.
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' ' ~ CA 02439087 2003-08-20 .
05-02-2003 N00200071
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In an important embodiment of the invention, the element for measuring dis-
tance is included in the acoustoelectric transducer. The transducer may then
be
s constituted by elastic piezaelectric foils suspended in a surrounding frame
and
having a massive centre body, the centre body containing the element for
measur-
ing distance.
The element for measuring distance may be and ultrasound echo range fin-
der. The ultrasound echo range finder may comprise two piezoelectric elements,
one for emitting a narrow ultrasound beam forwards toward the sound emitter,
and
one for receiving ultrasound echo from the sound emitter.
AMENDED SHEET
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WO 02/074010 PCT/N002/00071
Alternatively, the element for measuring distance may be a laser range
finder.
An inside compartment in the microphone housing may contain circuitry for
generating, respectively interpreting signals to, respectively from the
element for
measuring distance. Parts of the circuitry may be adapted for generating ultra-
sound oscillations for exciting a piezoelectric ultrasound transmitter
element, and
other parts of the circuitry may be operative for receiving and interpreting
received
signals from a piezoelectric ultrasound receiver element.
Alternatively, parts of the circuitry may be adapted for generating control
signals for emitting light from a laser element in the element for measuring
dis-
tance, and other parts of the circuitry may be operative for receiving and
interpre-
ting received reflection signals from a light detector in the distance
measuring ele-
ment.
In one embodiment of the microphone of the invention, the microphone in-
~s eludes a circuit device for utilizing the measured distance, said circuit
device hav-
ing at least one function among a function group that comprises
shutting down transfer of sound-representing signals from the microphone,
adjusting a gain factor as a function of measured distance, and
adjusting an equalizer setting as a function of measured distance.
ao In one further embodiment of the microphone in accordance with the inven-
tion, the element for measuring distance and circuitry attached thereto, are
also
adapted for sound detection through demodulation of a reflection signal from
the
sound emitter, said reflection signal, being a high frequency signal,
receiving sup-
erposed sound modulation from the sound emitter and from ambient noise.
zs In the following, the invention shall be discussed in closer detail, going
through exemplary embodiments, and in this connection it is referred to the
appen-
ded drawings, in which
Fig. 1 shows a microphone in accordance with the invention, in an embodi-
ment with a cable,
so Fig. 2 shows a microphone in accordance with the invention, with a wireless
transmission system,
Fig. 3 shows the same microphone as Fig. 1, however without a micro-
phone housing enclosure,
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3
Fig. 4 shows the top parts appearing from Fig. 3 in closer detail, and
Fig. 5 shows the sound transducer of the microphone.
First it must be pointed out that the embodiments mentioned herebelow, are
only meant to be examples of how to realize the microphone in accordance with
s the invention, while limitations should only appear from the appended
independent
claim. Hence, the microphone of the invention is not specified in detail with
regard
to how to process, in the microphone, sound that has been picked up, nor with
re-
gard to how the sound is processed by equipment for processing signals
transfer-
red from the microphone, nor with regard to how electric sound-representing
sig-
nals are transferred from the microphone, for instance via an attached cable
or via
a wireless transmission system. Hence, in Figs. 1 and 2 appear two embodiments
of the microphone 1 in accordance with the invention, with transmission
through a
signal cable 2 (Fig. 1 ), respectively via a radio transmitter 3 and antenna 4
(Fig. 2).
For the rest, only outer details appear in Fig. 1 and 2, while the details
that are
~s essential for the present invention, appear from the following Figs. 3, 4
and 5.
In Fig. 3 appears a microphone that corresponds to the one shown in Fig. 1,
however without an outer microphone housing 5 (Fig. 1, Fig. 2). The same micro-
phone top 6 as in Fig. 1 and Fig. 2 appears also in Fig. 3 and Fig. 4, but
these
figures show an acoustoelectric transducer 7, shown in better detail in Fig.
5. The
2o primary function of the transducer 7 is of course picking up sound
vibrations trans-
ferred through the air from a sound emitter, for example from the mouth of an
art-
ist, and further transferred through the grill-shaped microphone top 6. The
trans-
ducer 7 as shown has an outer frame 8, and supported rigidly therein via beams
9,
an inner frame 10. Inside frame 10 there is a number of piezoelectric membrane
as foils having sector shape and small radial slits 12 between sectors.
Centrally, the
foil pieces 11 are attached to a centre body 13. When sound waves hit the
sector-
shaped foil membranes, they get into an oscillatory state, and the movements
re-
sult in generation of voltages in the piezoelectric foils. These voltages are
output
by means of wires 14, each respective foil piece 11 being equipped with
separate
so signal wires. Such a transducer, intended to be used in a preferred
embodiment of
the microphone of the invention, is discussed in applicant's previous US
patent ap-
plication having serial number 09/788,607, filed 21 February 2001. In this US
pat-
ent application appear the following variants, for which priority is claimed
in the
present invention:
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4
In the very centre body 13, piezo-elements 15, 16 have been laid in, i.e. one
piezo-element 15 for transmitting vibrations, and one piezo-element 16 for
receiv-
ing reflected vibrations. Signal wires to/from the piezo-elements of the
centre body
do not appear in Fig. 5, however they follow paths on sectors 11 from the
centre
s body 16 and out to signal wires 17 appearing in the figure. The piezo-
elements 15
and 16 are in this case cast-in "half moons" of a piezo-material. The manner
of
operation will be e.g. that the centre body piezo-element 15 transmits high-
frequ-
ency vibrations, preferably in the range 5-10 MHz (however not limited to such
a
range), in order to make an echo sounder measurement, possibly an echo Doppler
investigation for more precise examination of the movement mode of the sound
emitter.
Reflected vibrations are picked up by means of element 16. The ultrasound
beam that is transmitted from the centre body, can be very narrow and
directional,
and may for example pass centrally out through the microphone top 6, i.e.
through
~s a special centre hole. The two "crescent shaped" piezo-elements 15 and 16
can
also have a parabolic or approximately parabolic curvature, to achieve
transmis-
sion of a narrow beam, and for correspondingly directional reception.
The different sectors of the sound receiving element with piezo-foils 11 can
also be used both for transmission and reception, however this is of less
interest in
zo a microphone embodiment. The separate sectors provide mainly possibilities
for
electronic signal combinations, in order to cancel out noise.
Another feature of the transducer element is the tautening system on the
underside of the centre frame 10. A system of stays 18 provides support for a
tightening screw 19 that, when operated, is able to pull the centre body 13
some
zs distance in a downwards direction, so as to impart a downward slanting
position
toward the centre body 13, for the foil sectors 11 inside centre frame 10,
thereby
giving the whole active part of the transducer a somewhat more "parabolic"
shape,
and hence more directional. If the centre screw 19 constitutes a stiff
coupling all
the way up to the centre body 13 on the underside, only with a possibility for
ac-
3o commodating rotation, the centre body 13 is locked with regard to vibration
in a
vertical direction, and the foil sectors 11 will then only be able to vibrate
between
such a fixed centre body 13 and a fixed inner frame 10. But if a link between
the
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tightening screw 19 and the centre body 13 is equipped with an elastic part,
the
whole system of foil sectors and the centre body will still have a vibrational
mode
in the vertical direction, however modified by the influence of the elastic
link.
Signals to/from the active elements 11, 15, 16 in the transducer are forwar-
s ded along signal wires 14, 17 (Fig. 5), as mentioned, and further to/from
the base
unit 20 shown in Fig. 3. This base unit 20 may contain signal processing equip-
ment, for example an AID converter, a controllable/programmable equalizer, amp-
lifier and other equipment. On the other hand, it is also possible to convey
the sig-
nals to/from the active elements directly via wire 2 if the microphone is of a
type
1o with cable attachment. However, with regard to the range finder system with
which
the microphone is equipped, it is of particular interest with internal
circuitry, contai-
ned in base part 20, for generating ultrasound signals for the piezo-element
15, as
well as circuitry for reception and interpretation of received reflection
signals from
piezo-element 16. The base part 20 will preferably contain a power source in
the
~s form of a battery, which power source will also be necessary for operating
possible
other circuitry as mentioned above, and in the case with wireless transfer to
exter-
nal equipment (Fig. 2), also for operating a radio transmitter/receiver in
unit 3
(Fig. 2). Furthermore, the circuitry for interpretation of range finding
signals will be
operative for utilization of the measurement result, for example by shutting
down
ao transfer of sound-representing signals from the microphone if the distance
to the
sound emitter exceeds a certain predefined threshold value. Correspondingly,
it
will be possible to utilize the range finding result for adjustment of a gain
factor of
the built-in amplifier, possibly for an amplifier in the external equipment,
and then
in such a manner that a short distance may entail attenuation, while a longer
mea-
ns sured distance will entail increased gain. In addition it is possible to
influence a fre-
quency curve, i.e. an equalizer setting, as a function of measured distance,
for in-
stance with a basis in known relations between distance to sound emitter and
pre-
sence of cerfiain undesired frequency crests or frequency dips in the sound
result.
As regards cancelling noise, the centre body with its range finding system
so also has a double function. It is a fact that the high frequency
ulfirasound signal
that is transmitted from element 15 to be reflected from the sound emitter,
after re-
flection also will receive a slower vibration as a superposition, namely the
sound of
interest from the sound emitter, and possibly also some noise from the
surround-
ings. These slow sound vibrations ( that is, slow relative to the high
frequency
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used in the actual range finding measurement) can be separated from the high
frequency oscillations, by means of signal processing, and they can be used as
a
basis for signal processing for the sound vibrations that are also picked up
through
the foil sectors 11, and in particular with regard to cancelling noise and
undesired
s sounds from the sound signals. The circuitry in base element 20 can also be
adap-
ted for such a function.
So far, only an ultrasound element arranged centrally in the very sound
transducer, has been mentioned as a range finder element. It is also possible
to
arrange a similar ultrasound range finder in some other position on the micro-
~o phone, but with the same function and with the same type of connection to
signal-
processing circuitry.
Another type of range finder that is per se known, is a device utilizing a
laser beam, and it is possible to incorporate a small laser diode, possibly
with
micro-optics, in the same position as the unit shown in Fig. 5, namely in the
actual
~s centre body 13. A laser beam, preferably using infrared light, is then
emitted
through a corresponding opening in the microphone top 6, to be reflected from
the
sound emitter and back to a light detector arranged together with the laser.
Such a
laser range finder can also be arranged in some other place on the microphone,
for instance peripherally. (Such a range finder can be retrofit equipment.)
How-
zo ever, for obvious reasons a central position will be preferable.
Finally it must be mentioned that the present invention is one of several in-
ventions regarding a complete microphone, all of these inventions being made
subject of patent applications simultaneously, and it is referred to Norwegian
pat-
ent application no. 2001 5983 regarding "A song microphone with signal proces-
as sing equipment", Norwegian patent application no. 2001 5982 regarding "A
micro-
phone with variable ventilation", and Norwegian patent application no. 2001
5984
regarding "A microphone with exchangeable details". To the degree that these
simultaneously filed patent applications exhibit features suitable for
explaining or
completing features of the present invention, these applications are hereby
incor-
so porated in the present specification by reference.
