IMPROVEMENTS RELATING TO FOCUSING APPARATUS

Description

[0001] This invention relates to cones and concave reflectors which are used for focussing signals - electromagnetic or otherwise. Examples of these are the speakers in radios.

[0002] Such a reflector can be used as part of a distance sensing apparatus wherein an ultrasonic transducer situated in a recess is excited by an exciter means within a case to emit pulses of ultrasonic radiation, the conical or concave sides of the recess serving to define the field of view of the transducer. A problem with this design is that the momentthe signal exits from the recess it is free to begin to diverge. In diverging, a lot of the energy in the transmission signal is wasted as the distance to be measured is almost always directly in the forward direction of the transmitting beam. Spurious reflected signals can be received from obstacles outside the direct line to the target but in the field of view which can lead to erroneous readings of the distance to be measured. The reception of the reflected signals may well be very poor due to the size of the transducer and the inefficiency of the recess in collecting the reflected signals.

[0003] It is an object of the present invention to overcome some of the problems described above and to provide a focussing apparatus which will radiate a narrow beam and collect reflected signals from target objects directly in front of the cone and which will prevent spurious reflected signals from being collected.

[0004] According to the invention there is provided a focussing apparatus comprising a truncated cone shape having substantially the configuration of a cone with its apex removed and, a cone mounted coaxially within the truncated cone such that the mouths of the cone and the truncated cone both face in the same direction, characterised in thatthe cone is closed at its apex which lies at or near the plane of truncation of the truncated cone, a collar extends back from the truncated end of the truncated cone, and incorporates a transducer of the type which is capable of radiating and receiving sonic or ultrasonic signals, and the transducer is mounted on a support pillar within the collar such that the transducer is positioned near the truncated end of the truncated cone.

[0005] The cone and the truncated cone may have substantially identical angles of divergence, or if desired, the truncated cone could have a larger angle of divergence than the cone.

[0006] A resilient buffer is preferably included between the support and the transducer. Also the transducer may have a signal collecting plate mounted centrally thereon.

[0007] The invention also extends to a distance measuring device comprising focussing apparatus according to the invention as hereinbefore defined, and including a transducer and control circuitry for energising the transducer and processing signals received by the transducer and a display device for indicating results of a calculation of distance measured made by electronic circuitry.

[0008] The invention may be performed in various ways and preferred embodiments thereof will now be described with reference to the accompanying drawings, in which:

Figure 1 is a diagrammatic perspective view of one form of apparatus of this invention;

Figure 2 is a further diagrammatic perspective view of the apparatus of Figure 1;

Figure 3 is a diagrammatic perspective view of the central part of the apparatus in Figure 1;

Figure 4 is a longitudinal sectional view of the apparatus shown in Figures 1 and 2, indicating the path of transmitted and received signals;

Figure 5 is a view similar to that of Figure 4 illustrating a modified form of apparatus of this invention; and

Figure 6 is a drawing of a distance sensing and measuring apparatus incorporating a focussing device as shown in the previous Figures.

[0009] Referring firstly to Figures 1, 2 and 3 the apparatus comprises a truncated cone member 10, a cone 11, a transducer housing collar 12 and four ribs 13 projecting outwardly from the outer surface of the cone 11. The transducer housing 12 is open at both ends 14,15 and the end 15 is attached to the truncated open end 16 of the truncated cone member 10. The cone 11 is attached to the inside surface 20 of the truncated cone member 10 by means of the fixing ribs 13 in such a manner that the apex 17 of the cone 11 is situated in the centre of the plane of truncation, indicated by the dashed line A-A in Figure 4, of the truncated cone member 10 so that the mouth 18 of the cone 11 is facing in the same direction as mouth 19 of the truncated cone member 10.

[0010] The cone 11 in this case has a preferred inclusive acute solid angle of 54°, but this angle may be varied. Referring now more particularly to Figure 4, the truncated cone member 10 is shown having a larger acute solid angle than the cone 11. In this example the inner surface 20 of the truncated cone member 10 diverges relative to the inner surface 21 of the cone 11. However the inner surfaces 20 and 21 of the cone 11 and of the truncated cone member 10, respectively, may converge relative to each other or they may be substantially parallel.

[0011] Figure 5 illustrates a focussing device of slightly modified form from that shown in Figure 4 and in particular illustrates how a transducer 30 will desirably be mounted within the collar 12. Thus the end of the collar 12 is enclosed by a plate 31 and carries a central mounting pillar 32 on which a plate-like ceramic transducer 30 is mounted via a resilient buffer 33. A collecting plate 34 is positioned on top of the transducer plate. A pair of wires 35 is connected to the transducer plate 30 by means of which an electric current may be supplied to excite the transducer plate.

[0012] A signal 22 from the transducer 30 housed within the transducer housing 12 will be transmitted in the direction of the cone 11. Most signals from the transducer 30 will strike the outer surface 23 of the cone 11 at an angle to the horizontal of approximately 27° and thereafter will be reflected outwards towards the inner surface 20 of the truncated cone member 10 substantially in a plane parallel to the plane of truncation A-A of the truncated cone member 10. On striking the inner surface 20 of the truncated cone member 10 the signal 22 will be reflected towards the mouth 19 of the truncated cone member 10 and in a plane substantially perpendicular to the plane of truncation A-A. In this way a substantially parallel beam of radiation can be made to travel in a specific direction, although the beam will tend to diverge as the distance it traverses increases.

[0013] If the signal 22 is reflected from an obstacle then it may return to the transducer along a substantially similar path to that followed when being transmitted as described above. Ideally a major part of any signal transmitted from the transducer (not shown) situated in the transducer housing 12 will be reflected by obstacles and follow a path similar to but in the opposite direction to that of the signal 22 as described above, and will be received in the transducer again. Reflections such as these which follow the same path on reflection as followed on transmission shall be called "direct reflections".

[0014] "Indirect reflections" are also received and these are signals which are reflected back to the transducer but which do not follow the same path as on transmission. Signals such as that following the path 24 shown in Figure 5 shall be called "indirect reflections". An example of an indirect reflection will now be described. A signal 24 is transmitted from the apparatus as described above and because of the shape and/or direction of an object from which it is reflected a signal is deviated slightly. On reflection back to the apparatus the signal 25 will not travel along the same path as on its transmission journey, but may be received by the apparatus and then undergo a multiplicity of reflections between the inner surface 20 of the truncated cone member 10 and the outer surface 23 of the cone 11 before finally entering the transducer again.

[0015] It will be appreciated that the focussing device shown in Figure 4 will operate in much the same manner as that shown in Figure 5 and sample signals 22, 24 and 25 are illustrated in the same manner.

[0016] The narrowness of the angle of the beam produced by the focussing device will depend upon the angles formed by the inner surface of the inner cone member 10 and the outer surface of the cone 11. Requirements may vary for different purposes and the desired beam angle can be achieved for any particular purpose by incorporating a cone 11 of a shape sufficient to produce the desired beam angle. For most purposes it is envisaged that a projection angle of between 2° and 5° will be desirable. The shape of the inner surface of the truncated outer cone 10 determines the beam intensification and the changes in size will naturally modify the overall collection area for reflected signals.

[0017] While the invention has been described primarily for use in focussing a sonic or ultrasonic signal it is applicable to other forms of signals and radiation. The apparatus may be used with equipment and signals for measuring the dimensions of a room, the height of a ceiling, or height of a vehicle and as a focussing and/or distance finder in cameras and rifles, for use by reversing vehicles, and for direction finding in foggy conditions.

[0018] Such equipment is illustrated diagrammatically in Figure 6 and comprises a hand-held box 36 which incorporates a built-in power supply and electronic circuit unit 37 which feeds signals to the transducer 30 through the wires 35 and processes reflected signals which are received by the transducer 30. The unit 36 controls a display device 38 which indicates a distance measure as calculated by the unit 37. A button 39 is provided for switching on the device when in use. The box 36 may also carry a direction finding device comprising a halogen bulb 40 powered from the power supply unit 37 which can produce a narrow beam of light over a relatively long distance even if a low voltage power source is used, by passing the light through a series of prisms 41. The light beam can be aimed at a target object so that the beam of sonic or ultrasonic signals will also be targetted onto that object.

[0019] The apparatus may be constructed in various ways other than those as shown. For example the apparatus may be constructed in one piece, such as in a moulding process or it may be constructed by fixing together the cone 11, the truncated cone member 10, the ribs 13 and the transducer housing 12. In a further embodiment the truncated cone member 10 may be constructed from a plurality of detachable sections which for instance would facilitate storing of the apparatus.

[0020] The major advantages of this apparatus over prior known focussing systems are

1. The apparatus has strong directional focussing properties.

2. The apparatus can focus a more powerful signal.

3. The apparatus will minimise false readings by keeping the signal beam as narrow as possible and the apparatus will also be able to pick up much weaker signals which are reflected from objects a greater distance away.

[0021] The truncated cone 10 acts as an ear to collect the reflected signals but it will only collect substantially signals from a direction in which they were transmitted and will thus tend to eliminate false readings.

Claims

1. A focussing apparatus comprising a truncated cone shape having substantially the configuration of a cone with its apex removed and, a cone mounted coaxially within the truncated cone such that the mouths of the cone and the truncated cone both face in the same direction, characterised in that the cone (11) is closed at its apex which lies at or near the plane of truncation of the truncated cone (10), a collar (12) extends back from the truncated end of the truncated cone (10), and incorporates a transducer (30) of the type which is capable of radiating and receiving sonic or ultrasonic signals, and the transducer is mounted on a support pillar (32) within the collar such that the transducer is positioned near the truncated end of the truncated cone.

2. A focussing apparatus according to claim 1, further characterised by a resilient buffer (33) between the support pillar and the transducer.

3. A focussing apparatus according to claim 1 or claim 2, further characterised in that the transducer has a signal collecting plate (34) mounted centrally thereon.

4. A focussing apparatus according to any one of claims 1 to 3, further characterised in that the cone (11) is replaceably mounted within the truncated cone (10).

5. A distance measuring device comprising focussing apparatus according to any one of claims 1 to 4, further characterised by control circuitry (37) for energising the transducer (30) and for processing signals received by the transducer and a display device (38) for indicating results of a calculation of distance measured made by the control circuitry.

6. A distance measuring device according to claim 5, further characterised by means (40, 41) for projecting a continuous light beam mounted on or in the device to act as a direction finder.

Ansprüche

1. Fokussiergerät mit einer Kegelstumpfform, die im wesentlichen einem Kegelstumpf entspricht, dessen Spitze entfernt ist, und mit einem Kegel, der in dem Kegelstumpf koaxial derart angeordnet ist, daß die Öffnungen des Kegels und des Kegelstumpfes in die gleiche Richtung weisen, dadurch gekennzeichnet, daß der Kegel (11) an seiner Spitze geschlossen ist, die in oder nahe der Abtrennebene des Kegelstumpfes (10) liegt, daß sich ein Kragen (12) von dem abgetrennten Ende des Kegelstumpfes (10) nach rückwärts erstreckt, der einen Wandler (30) enthält, welcher in der Lage ist, Schall-oder Ultraschallsignale auszustrahlen und zu empfangen, und daß der Wandler auf einer Tragstütze (32) innerhalb des Kragens nahe des abgetrennten Endes des Kegelstumpfes angeordnet ist.

2. Fokussiergerät nach Anspruch 1, gekennzeichnet durch einen nachgiebigen Puffer (33) zwischen der Tragstütze und dem Wandler.

3. Fokussiergerät nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß der Wandler eine zentral angeordnete Signal-Sammelplatte (34) aufweist.

4. Fokussiergerät nach einem der Ansprüche 1 bis 3, dadurch gekennzeichnet, daß der Kegel (11) auswechselbar in dem Kegelstumpf (10) angeordnet ist.

5. Entfernungsmeßerät mit einem Fokussiergerät nach einem der Ansprüche 1 bis 4, gekennzeichnet durch eine Regelschaltung (37) zum Erregen des Wandlers (30) und zum Verarbeiten der von dem Wandler empfangenen Signale, und durch eine Anzeigevorrichtung (38) zum Anzeigen der Ergebnisse einer von der Regelschaltung durchgeführten Berechnung einer gemessenen Entfernung.

6. Entfernungsmeßgerät nach Anspruch 5, gekennzeichnet durch an dem Gerät angebrachte, als Peileinrichtung dienende Mittel (40, 41) zum Ausstrahlen eines kontinuierlichen Lichtstrahles.

Revendications

1. Appareil de focalisation comportant une pièce en tronc de cône présentant sensiblement la forme d'un cône avec son sommet enlevé, ainsi qu'un cône monté coaxialement à l'intérieur du tronc de cône de façon telle que les embouchures du cône et du tronc de cône se trouvent en face de la même direction, caractérisé en ce que le cône (11) est fermé à son sommet, qui se trouve dans le plan terminal du tronc de cône (10) ou près de ce plan; en ce qu'un collet (12) s'étend à l'arrière, depuis l'extrémité tronquée du tronc de cône (10) et loge un transducteur (30) du type capable de radier et de recevoir des signaux soniques ou ultrasoniques; et en ce que le transducteur est monté sur une colonne support (32) située dans le collet de façon telle que le transducteur est placé près de l'extrémité tronquée du tronc de cône.

2. Appareil de focalisation selon la revendication 1, caractérisé en outre par un tampon élastique (33) entre la colonne support et la transducteur.

3. Appareil de focalisation selon la revendication 1 ou la revendication 2, caractérisé en outre en ce que le transducteur comporte une plaque collectrice des signaux (34) qui y est montée dans l'axe.

4. Appareil de focalisation selon l'une quelconque des revendications 1 à 3, caractérisé en outre en ce que le cône (11) monté à l'intérieur du tronc de cône (10) peut être échangé.

5. Dispositif de mesure des distances comportant un appareil de focalisation conforme à l'une quelconque des revendications 1 à 4, caractérisé en outre par un circuit de commande (37) pour mettre sous tension le transducteur (30) et pour traiter les signaux reçus par le transducteur ainsi que par un dispositif d'affichage (38) pour indiquer les résultats d'un calcul de mesure de distance effectué par le circuit de commande.

6. Dispositif de mesure des distances selon la revendication 5, caractérisé en outre par des moyens (40, 41) pour projeter un faisceau continu de lumière montés sur le dispositif pour agir comme détecteur de direction.

Drawing