WO1982002088A1

WO1982002088A1 - Optoelectrical magnetic compass

Info

Publication number: WO1982002088A1
Application number: PCT/FR1981/000164
Authority: WO
Inventors: Albert Wache
Original assignee: Albert Wache
Priority date: 1980-12-15
Filing date: 1981-12-15
Publication date: 1982-06-24
Also published as: EP0066595A1

Abstract

The device comprises included in a casing of reduced overall dimensions: a free rotating rose provided with magnetic orientation means and in the bottom of which there is arranged a narrow radial slot; at least a potentiometric track; and a light reflector generator separated from said track by the rose forming shutter. The casing (19) is mounted with a cardan system and is provided with contact strips (22-23 and 24-25) providing the electric connections required to the supply source. The elements are arranged so that the relative motions between the casing and the rose determine the informations and eventually the control signals required. Applications: among others, automatic pilot control device for ships or other moving vehicles, repeater compass, warning compass for head deviation, and all angle detectors.

Description

MAGNETIC OPTO-ELECTETIC COMPASS.

The present invention relates to an opto-electric magnetic compass intended more particularly to be used as an autopilot control member for a ship or other mobile machine, but without excluding the application to other uses such as repeater compass, d compass departure alert, among others ...

We know that in all autopilot systems it is necessary to control the ship's course to a chosen heading called "set point", which is generally given with respect to geographic North or magnetic North.

The information element of the autopilot is then constituted by a device which delivers a signal whose characteristics are a function of the angle formed by the route actually followed by the mobile and the set heading.

On autopilots this element of information is most generally constituted by a blind magnetic compass, the movable rose of which is provided with magnets and perforated with a slot which moves between photoelectric elements and an appropriate light source; other systems include roses made of polarizing material moving in front of two polarizing screens placed orthogόnally to the center of the rose, or even include roses making it possible to obtain degraded lighting. All these well-known devices are designed to give a voltage V varying as a function of the angle α formed by the route actually followed by the mobile and the heading set, but they are not free from several drawbacks which should be indicated. :

- difficulty in obtaining with these devices that the voltage variation: V = f (α) is linear over a large sea deviation, which is however almost always sought;

- the use of photoresist obscured at a given time has the consequence that these devices have very high output impedances, which, in particular on board ships, constitutes a serious drawback for remote use;

- variation in the characteristics of the photosensitive elements used due to aging, affecting the fidelity of the device over time;

- difficulty in obtaining voltage variations V = f (α) sufficient to be usable when the angle α exceeds 50 to 60 ^⍜ . In principle, with polarizing screen systems, you cannot exceed 45 ^⍜

- to obtain sufficient precision, the slits (or the pairs of lighting, photoresistors) must be relatively distant from the axis of the rose, moreover in the case of roses produced with polarizing screens or screens with degraded light, the lighting-photosensitive element pairs must be placed outside the inscribed circle in which the magnets are located. This and the fact that the rose itself must be notable To extend beyond the light axes in order to prevent interference with any stray light require roses of a certain size and therefore relatively large compasses.

The compass according to the invention eliminates all the drawbacks which have just been listed.

It basically includes:

- a mobile rose oriented by magnetic means and in which a narrow slit is made;

- at least one photoresistor track constituting a potentiometric track;

- a light reflector generator separated from this track by the rose and projecting light over the entire surface of the photoresistor track, this light can only avoid this track by the slit made in the rose.

The entire device is housed in a removable housing in two parts, placed inside two concentric rings forming a support for the gimbal, the outer ring being fixed. It is completed by flexible electrical connection means allowing all the required movements of the housing, which is suitably ballasted to remain horizontal whatever the movements made by the support, caused for example by the gite or the pitching if it is of a ship. It will appear from the following description that the compass considered not only eliminates the drawbacks of the prior devices, but also has the particularly important advantage of being a very small footprint and in addition not to be sensitive to the possible aging of the photoresist elements.

In the appended drawing which gives non-limiting embodiments in accordance with the invention:

Figure 1 shows schematically in exploded view the components of the compass.

Figure 2 shows in schematic section the same elements as in Figure 1 after installation inside the housing.

FIG. 3 represents the bottom of the rose and the associated potentiometric track in isolation.

Figures 4 and 5 show, also schematically, the generator-reflector assembly respectively when the light source is a lamp and when this source is a light emitting diode.

Figure 6 is an overall view of the housing including the compass, its gimbal support means and flexible means for electrical connection of the compass to the power source.

Figures 7, 8 and 9 illustrate the displacement of the flexible electrical connection means during the pivoting of the housing.

FIG. 10 represents an alternative arrangement concerning the opto-electric potentiometric device.

FIG. 11 represents the electrical diagram of FIG. 10.

Figure 12 shows a diagram of variations Of voltage.

Figure 13 shows another variant of the pσtentiometric device.

In FIGS. 1 and 2, the reference 1 designates the mobile rose which, in this example, is provided with vertical walls giving it a general shape of a bowl. The bottom of this bowl is provided with two linear magnets 2 arranged parallel to the diameter passing through the center of the rose, on either side of a short radial slot 3 made in said bottom.

The latter comprises in its center a clamp 4 resting on a pivot axis 5 fixed in the lower part 6 of the housing. Pivot 5 allows the rose to move freely in rotation and to take a certain inclination (generally limited to ± 15 ^⍜ ).

The light generator-reflector assembly 7 is integral with the upper part 8 of the housing. It is placed inside the bowl 1 a short distance from the bottom of the latter. 11 comprises a light source 9, such as a lamp in this example, associated with a tubular reflector comprising two parts, one cylindrical 7a which makes it possible to fix it to the housing 8, the other 7b, of frustoconical shape. The latter fulfills the prism functions as will be described later. In this example the lamp 9 is fixed in a perfectly polished tube housed inside the reflector. The housing 8 is made of an opaque material. The parts 7a and 7b of the reflector are metallized on the outside so as to improve the optical characteristics while preventing part of the light to escape.

A support 10 of a photoresistor track in the form of an open crown is integral with the bottom of the lower part 6 of the housing, the surface of which is transparent at least for the part facing the track.

A ballasting means such as a lead P is fixed to the lower part 6 of the housing so as to ensure the horizontal retention of the housing assembly 6-8 which is mounted on a cardan support which will be described later in the course from the description of Figure 6.

In FIG. 3, the magnets 2 and the radial slot 3 at the bottom of the bowl 4 are shown in isolation, as well as the support 10. The support 10 comprises a layer of photoresist material 11, a layer of a material with high resistance. 12 and a layer of a conductive material 13. This assembly 11-12-13 is constituted in a known manner so as to form a potentiometric track, the cursor of which is constituted by a luminous flux traversing the track 11. The assembly 11-12 - 13 affecting the shape of an open crown, it is obvious that the rotational movement of the bowl 4 is limited accordingly by means of stops, and the housing is provided with corresponding stops to limit the operation of the device at maximum ± 170 ⍜ in either direction.

In FIG. 4 which shows in section the generator-reflector assembly 7 in a more detailed although schematic manner, it can be seen that the rays emanating from the lamp 8 are reflected 90 ° circularly by any the frustoconical wall 7b forming a reflector. As a result, the light flux is directed towards the bottom of the bowl over the entire path that the slit 3 can travel depending on the position which the latter occupies under the action of the magnets 2. Thus an opto-electric potentiometer is produced particular whose slot 3 constitutes the cursor.

In FIG. 5, the light source of FIG. 4 constituted by a lamp 9 such as that with filament is replaced by a light-emitting diode 14 whose light flux is reflected by the conical part 15, so that the reflector 7 intervenes under the conditions required to form the light circle defined above.

Reference will now be made to FIG. 6 to describe an embodiment of a gimbal support for the housing 19. The two elements of this support, of square shape, are designated by the references 17 and 18 respectively.

In this figure, the references 16 designate the attachment points of the fixed outer "ring" 17 which can be placed at any suitable point. On this "ring" 17 is pivotally mounted around an axis XX "the inner ring" 18. Inside the "ring" 18 can pivot along the YY axis the housing 19 formed of two parts 6- 8 (Figures 1 and 2).

It is thus understood that the two "rings" 17 and 18 indeed constitute a support allowing the pivoting of the housing 19 in all planes. We will also describe by means of this same figure 6 the electrical connection means characteristic of the invention. According to the latter, the electrical connection between the opto-electric potentiometer and its light source to the current supply source is constituted by two curved bridges respectively designated by the references 20 and 21, each formed of a plurality of parallel flexible wires. suitably isolated, three in this example where it is assumed that the potentiometric track and the lamp are supplied with the same voltage.

The ends of the painted thus formed are respectively connected to lugs secured to flexible supports such as printed circuits 22 and 23 for the bridge 20, and 24 and. 25 for deck 21.

Thus, the electrical connection from the support 22 is carried out by the bridge 20, the support 23 secured to the inner "ring" 18, the support 24 also secured to this "ring" and electrically connected to the support 23 by rigid connections . Finally, the required electrical connection is provided to the elements included in the housing 19 by the support 24, the bridge 21 and the support 25 secured to the housing 19.

The supports 23 and 24 and their connections can be replaced by a single flexible printed circuit bent at 90⍜ eno 26. The conductive wires can advantageously be formed by a phosphor bronze-type spring wire.

In FIGS. 7 and 8, the displacement from D to E of the central conductor wire of the bridge 21 fixed to the support is shown when the housing 19 pivots, for example by 45⍜ around the axis YY in "! 'Ring" 18 . FIG. 9 shows more precisely the angular displacement of the support 25 and of the three flexible conductors which are fixed to it. It can be seen that this DOE angular displacement is not significant. Consequently, the return torque is very low. On the other hand during displacement the three conductors remain practically parallel.

It should be noted that the arrangement of the generator-reflector assembly 7 inside the cuvette and that the light-tight housing surrounding this cuvette and the generator-reflector assembly prohibit any penetration of outside stray light on the track. photoresist.

On the other hand, the mode of range of the bowl on the housing allows, as can be seen, not only a rotational movement but also slight tilting movements whose amplitude is limited, the length of the slot 3 being provided so that the photoresist track 11 is always under the effect of light projection in the event of an inclination of the bowl.

Finally, the light beam will sufficiently illuminate the photoresist part of the track so that its resistance is low (generally less than 50 KB). If the resistance of the track itself is low, the voltage will therefore be supplied by a low impedance source. .

The aging of the photoresist part of the track which is manifested by the variation of its resistance over time will have no effect on the voltage delivered, which makes the characteristics of the device insensitive to aging. We will now describe two variants consisting in substituting for the single track in the form of an open crown (as shown in FIG. 3), two tracks, at least one of which is completely circular. Such an arrangement makes it possible to obtain a continuous information signal without blind spot.

In Figure 10 are shown two continuous concentric tracks 31 and 32. The outer track 31 is itself formed of three tracks 33a, 34a and 35a, respectively conductive, photoresist and resistant. The layout is identical for runway 32, with 33b, 34b and 35b.

Track 31 is connected to a current source at points A and B diametrically opposite, while track 32 is connected to this source at points C and D also diametrically opposite and arranged at right angles to AB of track 31, both diameters considered are therefore orthogonal. In addition, the conductive tracks 33a and 33b are each provided with an output connection, E and F respectively, the positions of which are indifferent.

Reference 36 designates the spot emanating from the light source.

FIG. 11 represents the electrical diagram of the two tracks 31 and 32.

When a spot located on a ray making an angle with A B hits the two tracks, an electrical circuit is represented represented by the diagram: one collects at the point E a tension Ve and at the point F a tension Vf

When α varies, these voltages are represented on the diagram which constitutes figure 12.

On this diagram we see that the voltage Ve gives for the angle α, similar information when α varies from O to 180⍜ and when α varies from 360⍜ to 180⍜.

However, if we look at how the voltage varies

VF, we note that;

and

However, it is easy to compare using known means (comparator circuit) the voltage,

and in this way, either to know the sign of α

either to add to V _E a fixed voltage equal to U to know α from O to 360⍜ also by means of known circuits (adder), in this case,

a way is thus obtained of knowing the angle α in a continuous manner.

Depending on the applications envisaged, this information can be used as it is or formatted appropriately using known means depending on the corresponding application.

In Figure 13 is shown an alternative embodiment also comprising two tracks. According to this variant, track 31 is completely circular. Track 32 being only semi-circular and constituted by two conductive tracks, respectively 37 and 38, arranged on either side of photoresist track 39. The connection points A, B, C, D are all distributed on the same diameter.

The spot striking all the tracks simultaneously, if O <α <π, we collect a signal in F, and if π <α <2 π, we do not collect a signal in F and this information can be interpreted as above.

It is understood that the embodiment described and shown is in no way limiting and that without departing from the scope of the invention, any modifications and variants may be made concerning the number, the shape and the composition of the constituent elements, which may be substituted. all means providing the same effects. In this order of idea, the linear magnets 2 may be replaced by a suitably oriented radially magnetized ring.

It is obvious that the device which is the subject of the invention being an angle indicator, the rose of which constitutes a shutter, the latter can be replaced by a simple shutter driven by a concentric control pin indicating the relative positions whose knowledge is required.

Claims

1. Magnetic compass of small bulk, characterized in that it includes an opto-electric potentiometer and in combination: a) a free rotating roae (1) provided with magnetic orientation means (2) and in the bottom of which a short and narrow radial slit is practiced (3);

b) a housing in two parts, the lower part (6) constituting a support on which the so-called mobile rose rests by means of a clamp (4) and a pivot (5) allowing free rotation as well as a slight inclination limited in amplitude, the upper part of said housing (8) supporting a generator-light reflector assembly (7);

c) an opto-electric potentiometric track in the form of an open crown comprising in juxtaposition a high resistance track, a photoresist track, a conductive track and integral with the bottom of said bottom part (6) of the housing, said bottom being made of material transparent at least for the part opposite the said opto-electric potentiometric track.

d) a light generator-reflector assembly comprising a light source (9) supplied with electric current and a reflector constituted by a tubular means formed by a cylindrical part (7a) and a frustoconical part (7b), said source light being disposed inside said frustoconical part so that the wall of the latter forms a reflecting prism, so that the light thus reflected circularly excites the photoresist track (11) at the point opposite said slot made in said movable rose (1);

e) cardan support means (17-18) ensuring the maintenance of the housing (I9, fig.7) in the required position;

f) flexible connection means ensuring the transmission of the information signal as well as the current supply of the light source;

2. Magnetic compass according to claim 1, characterized in that at the optoelectric potentiometric track in the form of an open crown are replaced two independent concentric tracks totally circular and of the same structure (31, 32), the two connection points to a source of current (A, B and C, D) being for each diametrically opposite and according to orthogonal diameters for one and the other of said tracks, so as to allow obtaining continuous information and proportional to the steering angle.

3. Magnetic compass according to claims 1 and 2, characterized in that one of the circular tracks (32) is replaced by a semi-circular track formed by two conductive tracks (37, 38) arranged on either side of the photoresist track (39), all the connection points to a current source (A, B, C, D) being arranged on the same diameter, those of the said semicircular track (C, D) being arranged on the same radius.

4. Magnetic compass according to claim 1, characterized in that the rose (1) takes the form of a curette with vertical walls, inside which is engaged the frusto-conical reflector (7b), so that only the light rays emanating from the source considered can pass through the slot (3) formed in the bottom of said rose (1).

5. Magnetic compass according to claim 1, characterized in that the magnetic means consist of a radially magnetized ring suitably oriented.

6. Magnetic compass according to claim 1, characterized in that the generator assembly (7) is constituted by an electroluminescent diode (14) disposed inside a reflector comprising two frustoconical prisms to obtain a double reflection of the light.

7. Magnetic compass according to claim 1, characterized in that the means of electrical connections between the fixed (17) and mobile (18) parts forming the universal joint suspension assembly consist of a plurality of flexible conductive wires arranged in parallel and developed in an arc so as to form a curved bridge (20 and 21) between their ends connected to supports such as flexible printed circuits (22 and 23 and 24 and 25) which can be animated with relative movements of pivoting according to an axis parallel to the development of said wires, which thus exert only a small torque that cannot slow down said movements.

8. Magnetic compass according to claim 7, characterized in that two of said supports (22 and 23) are respectively integral with the fixed ring (17) and of the inner ring (18), while two others of said supports (24 and 25) are respectively secured to said inner ring (18) and to the housing (19), the connection between said supports secured to said inner ring ( 18) being provided by rigid connections.

9. Magnetic compass according to claims 7 and 8, characterized in that the two supports integral with the inner ring (18) is replaced by a single flexible printed circuit which can be bent at 90⍜ (at 26).