Electronic converter for converting an acoustic signal into...

Details Electronic converter for converting an acoustic signal into... Electronic converter for converting an acoustic signal into...

2000-08-02

2003-06-10

Miska, Vit (Department: 2841)

Horology: time measuring systems or devices

Signalling means

Time condition responsive

C368S255000, C310S321000, C310S322000, C310S339000

Reexamination Certificate

active

06577559

ABSTRACT:

The present invention concerns an electronic converter for converting an acoustic signal into a pseudo-digital signal, in particular for controlling a microprocessor, as well as a timepiece including such a converter. The invention also concerns a two-directional communication method via acoustic waves between a transmitter unit and a receiver unit.
A system for processing personal data is known from U.S. Pat. No. 5,848,027 in the name of Biometrics, Inc. This system allows, for example, the performance of an athlete, such as a runner, to be monitored. It allows to record the date and time of the time for each lap or even the final time achieved by the athlete. The system also allows the values of certain physiological parameters to be stored such as the cardiac rhythm or an electrocardiogram (ECG) which reflect the effort made by the athlete during his sporting activity. All this information will then be transmitted, via an acoustic link, to a personal computer in which the information will be processed, analysed and finally displayed on the screen of said computer.
FIG. 1
annexed to the present Patent Application shows a preferred embodiment of the aforementioned Biometric system. This system includes a portable object such as a timepiece
1
, for example a digital display wristwatch, able to store data and subsequently transmit them. These data may be transmitted to a personal computer
2
in the form of acoustic “beeps” generating an acoustic pressure
4
which will be picked up by a microphone
6
. The timepiece may be any type of digital instrument controlled by a microprocessor and containing a piezoelectric element able to generate acoustic “beeps” for data transmission. Personal computer
2
is fitted with a sound card
8
connected to microphone
6
by a cable
10
. The computer is thus able to pick up acoustic pressure
4
generated by the acoustic “beeps” emitted by timepiece
1
. Said computer
2
may also be fitted with a display screen
2
.
As shown in
FIG. 2
of the present Application, timepiece
1
includes an internal microprocessor
14
which provides the timebase to said timepiece
1
. Microprocessor
14
may also control a storage programme
16
co-operating with an internal random access memory. Further, a piezoelectric element
18
is able to generate at its output a pre-selected tonality. Piezoelectric element
18
is thus used to generate the acoustic “beeps” similar to those generated by sound generator devices in most digital watches fitted with an alarm.
The Biometrics system described above advantageously allows personal data to be stored in a watch, then these data to be transferred by sound waves to a computer where they will be processed and analysed. This system is unfortunately not two-directional. It is thus not possible to transfer data from the computer to the watch, which considerably limits the possible applications of the Biometrics system.
Moreover, Swiss Patent No. 641 625 in the name of Seikosha, Tokyo (JP) is also known, which discloses an electric circuit for driving a piezoelectric vibrator.
FIGS. 3 and 4
annexed to the present Patent Application show, respectively by an electric diagram and by diagrams of the evolution of voltage levels as a function of time, the constitution and operating mode of a conventional drive circuit for a piezoelectric vibrator.
The electric circuit whose diagram is shown in
FIG. 3
includes a coil L
1
, connected to the output of a transistor T
R1
which is alternately “ON” and “OFF”. A piezoelectric vibrator P
1
is connected in parallel across coil L
1
. This electric circuit receives, on a connection input “a”, a square pulsed control signal corresponding to what is shown by curve A of
FIG. 4
whose abscissa represents the time “t” and whose ordinate represents the voltage “v”. From input terminal “a”, this signal is applied to the base of transistor T
R1
via a resistor R. When transistor T
R1
is kept “ON” by the control signal pulse, an electric current flows through coil L
1
from a direct-current voltage source +E while connection “b” of piezoelectric vibrator L
1
is connected to the electric circuit's earth in accordance with what is shown by curve B of
FIG. 4
(whose abscissa represents time “t” and whose ordinate represents voltage “v”).
It is to be noted that as long as transistor T
R1
is “ON”, no current flows through piezoelectric vibrator P
1
. The latter behaves in fact like a capacitor. The current “i” supplied by a capacitor is equal to the product C*dE/dt, where C is the capacitance value of the capacitor, and E the voltage across its terminals. In the present case, since E is a direct-current voltage, its derivate with respect to time is zero, and the current which flows in piezoelectric vibrator P
1
is also zero. It may also be noted that voltage “v” across the terminals of coil L
1
is given by the equation v=−L*di/dt=E, where L is the inductance value of said coil L
1
, and “i” is the current which flows through it. Consequently, the product L*di/dt is constant, which means that as long as transistor T
R1
is kept “ON”, the current which flows in coil L
1
increases linearly.
At the moment that transistor T
R1
passes in the “OFF” state at the trailing edge of each pulse of wave shape A, any accumulated energy in the coil is transmitted to the terminals of the piezoelectric vibrator, charging the latter at a much higher voltage than the supply voltage, and in the opposite direction. As can be seen on the wave shape B of
FIG. 4
, this oscillating voltage has a first positive pulse of great amplitude, followed by a second very damped out negative pulse. This great damping out is due to the fact that the voltage at connection point “b” which is connected to the collector of transistor T
R1
cannot exceed, during the negative alternance, the blocking voltage of the P-N diode which forms this collector, a blocking voltage whose value is usually of the order of 0.6 volts. Thus the efficient electric energy which makes piezoelectric vibrator P
1
operate is only given by the initial pulse which is of short duration, so that it is difficult to obtain high excitation of said vibrator P
1
. It is for this reason that one encounters the drawback of not being able to obtain a sufficiently high sound pressure level.
FIGS. 5 and 6
annexed to the present Patent Application show the solution provided by Seikosha to the aforementioned problem.
FIG. 5
is a diagram representing an electric drive circuit for a piezoelectric vibrator constituting an embodiment of the Seikosha invention.
FIG. 6
is a diagram of the voltage levels as a function of time at two locations of the circuit of FIG.
5
.
The electric circuit whose diagram is shown in
FIG. 5
includes a coil L
2
and a diode D connected in series across the output of a transistor T
R2
. A piezoelectric vibrator P
2
is connected in parallel across this series connection.
At the moment when transistor T
R2
passes to the “OFF” state at the trailing edge of each pulse of the square control signal (curve A, FIG.
6
), a voltage is induced in coil L
2
and is applied, via diode D which remains polarised in the conductive direction, to the terminals of piezoelectric vibrator P
2
(curve B, FIG.
6
). The voltage across the terminals of vibrator P
2
then remains blocked at its maximum level, since, at the beginning of the reverse voltage pulse in coil L
2
, diode D is polarised in the non conductive direction and blocks the return of the current. As can be seen by comparing voltage levels B of
FIGS. 4 and 6
, the energy which is provided to piezoelectric vibrator P
2
is much greater than that which was provided to piezoelectric vibrator P
1
of the prior art.
Consequently, the Seikosha invention allows a substantial increase in the acoustic pressure level. However, this invention does not suggest the use of a piezoelectric vibrator for receiving and digitising of sound wave trains.
The object of the present invention is to overcome the above problems and drawbacks as well as others by providing an elec

Affiliated with

Also associated with

Rating

Electronic converter for converting an acoustic signal into... does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Electronic converter for converting an acoustic signal into..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Electronic converter for converting an acoustic signal into... will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3089153