Electronic analog wristwatch comprising a compass and an altimeter function

This invention relates to an electronic analog compass device that can indicate different physical measurement values using the technique of an ultrasonic motor.

Conventional compasses are mechanical compasses consisting of a compass rose above which a free-moving compass needle is mounted on a pivot indicating north. Electronic digital compasses were invented at a later date. However, neither electronic analog compasses nor electronic compasses which make use of the technique of a ceramic ultrasonic motor have been invented to date. Even though this type of motor, also known as electric piezo motor, is currently being used in numerous applications (sonar, ultrasonic echo-sounding, echography, metallurgy, process control in different fields) it has never been applied to the movement of a compass needle.

Moreover, no compass to date has been designed which can indicate, in addition to the direction of the magnetic north pole, the altitude and the time with the same hands. There is no current mechanism that allows three different measurements, i. e. the magnetic north pole, the altitude and the time.

For indicating the magnetic north pole position and the time (hours and minutes) with the same hands, magnetic interferences occur when using quartz movements with a conventional motor, usually known as "Lavet" motor. "Lavet" motors operate with permanent magnets and electric coils. The distortion stray field caused by the permanent magnet has an influence on the earth’s magnetic field. Therefore the resulting deviation has an effect on the earth’s magnetic field as measured by the magnetic field sensors of the compass. The consequential problem is that in this case the sensors measure both the field resulting from the earth’s magnetic field and the magnetic field generated by the "Lavet" motor. Thus, the combination of a conventional quartz movement and an electronic compass function in one unit is impossible without complex numerical compensation.

Interferences result from the use of a conventional "Lavet" motor created by the magnetic field generated by the permanent magnet of the rotor. The invention has as its object to provide a solution to the problems caused by these inferences. Ultrasonic motors do not generate a disruptive magnetic field and therefore do not influence the magnetic field sensors of a compass. Thus a compass comprising of this type of motor can be used additionally and alternatively as altimeter and watch and the measurement of the earth’s magnetic field is possible without any problem. Ultrasonic motors generate electric fields which do not influence the measurement of the earth’s magnetic field.

The three functions of the compass (indication of the magnetic north pole position, the time and the altitude) can coexist without causing interferences.

The invention has as its object to create a compass using an ultrasonic motor which was mainly developed by the CETEHOR group (France). This compass is intended to allow the indication of the direction, the measurement of time and the geographic altitude with one pair of hands.

The advantage of this compass comprising an ultrasonic motor lies in its ability to indicate at least three functions with one pair of hands. This is made possible by the application of a ceramic piezo motor in the object of the invention.

Firstly, the said ultrasonic motor is amagnetic therefore by definition avoids inducing deviation of the magnetic field sensors of the compass. As this motor (unlike the "Lavet" motor) does not generate a magnetic field, it can neither interfere with nor neutralize the orientation of the hands in the direction of the earth’s magnetic field.

Furthermore, an additional advantage of ultrasonic motors is that they are bidirectional. This means that the hands can be moved in two directions as is the case in conventional compasses and altimeters. Since the piezo motor, in contrast to the conventional "Lavet" motor which is usually one directional, operates in two directions (by changing the frequency of heading) it is especially suitable for the functioning of a compass and/or altimeter.

A further characteristic of the ultrasonic motor is that it can generate great power at a low number of revolutions per minute and has a big static torque.
This type of motor facilitates the precise final adjustment and setting of the hands.
The hands can be driven directly without additional gears.

This specific characteristic makes the piezo motor extremely suitable for the functioning of a compass and an altimeter. This is particularly true for the final adjustment of the hands as it suppresses any kind of vibration caused by the free play of the gears or the inertia of the hand or the hands during the final adjustment. The hand or the hands do not settle down slowly (as is the case in conventional compasses or altimeters), but they indicate the determined final value immediately.

Thus, by employing an ultrasonic motor in an electronic compass there is no longer any friction created between the hand and the pivot as is the case in conventional mechanical compasses. This represents a great advantage for the final adjustment of the hand or the hands.

When the piezo motor is employed in the object of invention it facilitates a rapid and precise indication. The electronic measuring and determination of the earth’s magnetic field is realized immediately (within milliseconds) and without any loss of precision (optimal precision).

The invention will now be described in detail, with reference to the accompanying diagrams, in which:
FIG. 1 is a view of the interior of the object of invention;
FIG. 2 is a schematic diagram (electric circuit diagram) of the use of the piezo motor in the object of invention;
FIG. 3 is a view of the exterior of the object of invention with an example of the measurement of the altitude and direction by the compass.

With reference to these figures the illustrated device comprises two piezo motors that are placed above each other with motor (1) being connected to a long bidirectional hand indicating the minutes and motor (2) being connected to a short bidirectional hand indicating the hours of a time piece.

Two magnetic field sensors are arranged in such a way as to electronically measure the earth’s magnetic field wherein sensor (3) generates the vectorial signals required for measuring direction X and sensor (4) generates the vectorial signals required for measuring direction Y. The angle between the two sensors is 90°, so that the vectorial addition of both sensor signals (3) and (4) in a right angled coordinate system leads to the northern direction to be determined, provided that the plane between direction X and Y is parallel to the horizontal plane.

Moreover, the object of invention comprises two accelerator sensors (5 and 6) in the same housing wherein one is required for indicating direction X and the other for direction Y. These two sensors are needed for measuring the earth’s acceleration which is indispensable for the optimal and precise determination of the magnetic northern direction as soon as the plane between direction X and Y is no longer parallel to the horizontal plane. The measurement value provided by these two accelerator sensors allows for the calculation of the angle between the horizontal plane and the plane between direction X and Y. This information serves to project the measured vector onto the horizontal plane. Only the direction projected on the horizontal plane corresponds precisely to the magnetic northern direction.

The object of invention also integrates a sensor that is sensitive to atmospheric pressure (7) for determining the altitude.

A push-button is placed on the crown that can be operated by pressing it down in order to select the desired modes of function and display (compass for determining the magnetic northern direction, altimeter for determining the altitude, time piece for determining the time) while concurrently it facilitates the adjustment of the hands through rotation.

The object of invention comprises a microcontroller (9) necessary for the processing of the signals generated by the various sensors (magnetic field sensor, accelerator sensor, atmospheric pressure sensor). These signals are subsequently transmitted to the piezo motor connected to the minute hand (1) via an amplifier (10) and to the piezo motor connected to the hour hand (2) via a second amplifier (11).

The finished object of invention comprises a printed circuit board (12) on which the electronic components are soldered.

FIG. 2 is a view of the electric circuit diagram of the object of invention.

The different sensors (the magnetic field sensors (3) and (4), the accelerator sensors (5) and (6), the atmospheric pressure sensors (7)) generate electric analog signals that, in a first phase, are transformed into digital signals. This rapid digitalization of the signals is followed by a second phase wherein at first the digitalized information is linearized and then processed by a microcontroller (9).

This microcontroller in turn produces information that, in a last phase, is transmitted via amplifier (10) and (11) to the piezo motors containing a closed loop regulation for the positioning of the hands. The two piezo motors then transmit the calculated by the microcontroller to the hands.

FIG. 3 is a view of the exterior of the object of invention. Referring to this figure the illustrated device comprises a long bidirectional hand for the indication of the minutes as well as a shorter, broader hand for the indication of the hours (time piece function).

If the said compass is alternatively used as an altimeter, the smaller of the two hands indicates a precise and final measuring of the altitude in steps of 100 meters of altitude, while the other hand indicates the altitude in steps of 1000 meters of altitude. The combination of both hands results in a precise altitude reading. In the example of FIG. 3 the altitude amounts to 5150m.

Alternatively both indicators facilitate the reading of direction in degrees if they are used for the determination of the northern direction. Then they are aligned on a single axis in such a way that the angle between them amounts to 180°. In that position both hands become one single hand and indicate one given direction. In the example of FIG. 3 the compass is directed towards east north-east.

Claims

1. Electronic analog compass characterized in that each of its hands is connected to a ceramic ultrasonic motor (known as electric piezo motor).
2. Electronic analog compass according to claim 1 characterized in that said compass includes one or several sensors or magnetic field sensors for the electronic measurement of the earth’s magnetic field.
3. Electronic analog compass with electric piezo motor according to claims 1 and 2 characterized in that said compass comprises one or several accelerator sensors in order to measure the acceleration of the earth for optimum indication of the North pole position.
4. Electronic analog compass with electric piezo motor according to claims 1 to 3 characterized in that said compass includes one or several amplifiers connected to a microcontroller as well as a printed circuit board on which electronic components are soldered.
5. Electronic analog compass with electric piezo motor according to claims 1 to 4 characterized in that said compass incorporates an electronic analog altimeter.
6. Electronic analog compass with electric piezo motor incorporating an electronic analog altimeter according to claim 5 characterized in that the same pair of compass hands indicate both direction and altitude.
7. Electronic analog compass with electric piezo motor incorporating an electronic analog altimeter according to claims 5 and 6 characterized in that said compass includes at least one atmospheric pressure sensor in order to electronically measure the altitude.
8. Electronic analog compass with electric piezo motor incorporating an electronic analog altimeter according to claims 1 to 7 characterized in that said compass includes an electronic analog multifunction timepiece usually in the form of a wristwatch.
9. Electronic analog compass with electric piezo motor incorporating an electronic analog altimeter including an electronic analog multifunction timepiece according to claim 8 characterized in that the same pair of compass hands not only indicates direction and altitude but also time and alarm time.
10. Electronic analog compass with electric piezo motor incorporating an electronic analog altimeter including an electronic analog multifunction timepiece according to claims 1 to 9 characterized in that said compass comprises a push-button placed on the crown in order to select (by pressing the push-button down) the desired display and to adjust the position of hands by way of rotation.

SUMMARY

The electronic analog compass comprises an ultrasonic motor (also known as electronic piezo motor) integrating an electronic analog altimeter and an electronic analog multifunction timepiece usually in the form of a wristwatch.
This invention relates to an electronic analog compass device using the technique of an electronic piezo motor and thus, by way of the same pair of compass hands, provides for the measuring of different kinds of data (northern point of the compass, altitude and time).
The invention consists of two electronic piezo motors (1) and (2) including a facility for detecting the position of the hands with each motor being connected to a bidirectional hand. The invention comprises two magnetic field sensors (3) and (4), two accelerator sensors (5) and (6) as well as an atmospheric pressure sensor (7). The electric signals generated by the sensors are digitalized, then linearized and eventually processed by a microcontroller, which in turn generates signals that are transmitted via the amplifiers (10) and (11) to the motors. The amplifier (10) is connected to piezo motor (1) and the amplifier (11) is connected to piezo motor (2). In addition, the invention comprises a printed circuit board on which the various electronic components are soldered. Furthermore, a push-button placed on the crown of the compass allows the selection of the different modes of functioning and display as well as the adjustment of the hands. The invention is especially designed for sportsmen (e.g. divers), for military purposes (in the field of topography) and for radio amateurs.