NZ204236A - Beaming radiation by cone reflection - Google Patents

Description

2 0423 Priority Date(s>; /u- r- w Cemplete Specification Filed: Class: Publication Date: P.O. Journal, No: E- 8 AUG 1986 Patents Form No.

SvU'Oi- APPLIGAHT w.s.-,. iLiiilOH 24 He NEW ZEALAND PATENTS ACT 1953 COMPLETE SPECIFICATION "IMPROVEMENTS RELATING TO FOCUSSING APPARATUS" I,WE STANISLAW BOLESLAW CZAJKOWSKI, a British subject of 2 Corrib Drive, Clareview, Ennis Road, Limerick, Republic of Ireland, hereby declare the invention, for which I/we- pray that a patent may be granted to me/trs, and the method by which it is to be performed, to be particularly describe^ in and by the following statement /followed by page 1 A.) 2 042 "Improvements relating to focussing apparatus" 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.

Such a reflector can be used as part of a distance 5 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 10 that the moment the 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 15 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 20 in collecting the reflected signals.

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 MJ/MIO 204236 front of the cone and which will prevent spurious reflected signals from being collected.

According to the invention there is provided a focussing apparatus comprising a "truncated cone" as 5 hereinafter defined a cone, mounted coaxially within the truncated cone such that the apex of the cone lies at or near the plane of truncation of the truncated cone and such that the mouths of the cone and the truncated cone both face in the same direction/ and a transducer housing 10 mounted adjacent the truncated end of the truncated cone.

The term "truncated cone" is used herein to define a geometrical shape having substantially the configuration of a cone with its apex removed.

The cone and the truncated cone may have substantially 15 identical angles of divergence, or if desired, the truncated cone could have a larger angle of divergence than the cone. 'a collar which extends In the preferred embodiment said transducer housing: comprises/ from the truncated end of the truncated cone, this 20 collar can then house a transducer. Ideally the transducer will be of the type which is capable of radiating and receiving sonic or ultrasonic signals.

Advantageously the transducer is mounted on a support pillar within the collar.

A resilient buffer is preferably included between the support and the transducer. Also the transducer may a4*.

MJ/MIO -2- / (r \\ /kPRW86™| 3 204236 have a signal collecting plate mounted centrally thereon.

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

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. 2 042 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 5 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 2 0 of the truncated cone member 10 by means of the fixing ribs 13 in such a manner that the apex 10 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. 15 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 20 surface 2 0 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 25 parallel.

Figure 5 illustrates a focussing device of slightly MJ/MIO -4- 2 042 3 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 5 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 10 current may be supplied to excite the transducer plate.

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 15 the horizontal of approximately 27° and thereafter will be reflected outwards towards the inner surface 2 0 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 20 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 25 direction, although the beam will tend to diverge as the distance it traverses increases.

MJ/MIO 20423 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 5 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 10 these which follow the same path on reflection as followed on transmission shall be called "direct reflections".

"Indirect reflections" are also received and these are signals which are reflected back to the transducer 15 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 20 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 25 multiplicity of reflections between the inner surface 2 0 of the truncated cone member 10 and the outer surface 23 MJ/MI.0 2 042 of the cone 11 before finally entering the transducer again.

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

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. 1Q 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.

Such equipment is illustrated diagrammatically in 15 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 20 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 apparatus may be constructed in various ways other than those as shown. For example the apparatus may 25 be constructed in one piece, such as in a moulding process or it may be constructed by fixing together the MJ/MIO -7- 20423 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 5 facilitate storing of the apparatus.

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 15 distance away.

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.

MJ/MIO 9 204236

Claims (11)

WHAT WE CLAIM IS;

1. A focussing apparatus comprising a "truncated cone" as hereinbefore defined, a cone, mounted coaxially within the truncated cone such that the apex of the cone substantially at lies at or / the plane of truncation of the truncated cone and such that the mouths of the cone and the truncated cone both face in the same direction, and a transducer housing mounted adjacent the truncated end of the truncated cone.

2. A focussing apparatus according to claim 1, wherein the cone and the truncated cone have substantially identical angles of divergence.

3. A focussing apparatus according to claim 1, wherein the truncated cone has a larger angle of divergence than the cone.

4. A focussing apparatus according to any one of claims 1 to 3, wherein said transducer housing comprises a collar which extends back from the truncated end of the truncated cone.

5. A focussing apparatus according to claim 4, wherein the collar houses a transducer.

6. A focussing apparatus according to claim 5, wherein the transducer is of the type which is capable of radiating and receiving sonic or ultrasonic signals.

7. A focussing apparatus according to claim 5 or claim 6, wherein the transducer is mounted on a 10 204236 support pillar within the collar.

8. A focussing apparatus according to claim 7, including a resilient buffer between the support and the transducer.

9. A focussing apparatus according to any one of claims 5 to 8, wherein the transducer has a signal collecting plate mounted centrally thereon.

10. A focussing apparatus substantially as herein described with reference to the accompanying drawings.

11. A distance measuring device comprising focussing apparatus according to any one of claims 5 to 10, including control circuitry for energising the transducer, processing signals received by the transducer and calculating a measure of distance and a display device for indicating results of the calculation of distance measured made by electronic circuitry.