Flexible ultrasonic transducer and a transducer block

1. A flexible ultrasonic transducer comprising a flexible metal plate, a piezoelectric ceramics element attached on the plate, a first electrical conductor which is electrically conductive attached to the plate and an insulation covering which covers at least a portion of the metal plate, the metal plate comprising:

a first outer surface;

a second outer surface lying opposite to each other wherein the piezoelectric ceramics element is attached to the first outer surface wherein the dimensions of the first outer surface and the piezoelectric ceramics element are such that a first portion of the first outer surface is not covered with the piezoelectric ceramics element;

wherein the first electrical conductor is electrically conductive attached to at least one of a first portion of the second outer surface and the first portion of the first outer surface wherein the first portion of the first outer surface and the first portion of the second outer surface lie opposite each other and have about the same dimensions and positions in a plane wherein the metal plate extends; and

wherein at least a portion of the insulation covering covers the first portion of the first outer surface so that the piezoelectric ceramics element is arranged to be directly dry coupled to a surface of an object to be inspected by means of the transducer.

2. The transducer according to claim 1 , wherein the insulation covering is attached to the first outer surface.

3. The transducer of claim 1 , wherein the insulation covering also covers at least a second portion of the second outer surface wherein the first and second portion of the second outer surface do not overlap each other and together form the second outer surface.

4. The transducer of claim 1 , wherein the first electrical conductor is electrically conductive attached to the first portion of the second outer surface, wherein the second outer surface is not covered by the insulating covering at a position wherein the first electrical conductor is electrically conductive attached to the second outer surface.

5. The transducer of claim 1 , wherein the insulating covering also covers a circumferential edge area of the piezoelectric ceramics element; or wherein the insulating covering does not substantially cover a circumferential edge area of the piezoelectric ceramics element.

6. The transducer according to preceding claim 1 , wherein the insulation covering is flexible and comprises a flat tape.

7. The transducer according to claim 1 , wherein the transducer further comprises a metal electrode which is electrically isolated from the first metal plate wherein an outer surface of the metal electrode and the first outer surface of the first metal plate or the piezoelectric element lie at least substantially in a same flat plane.

8. The transducer according to claim 7 , wherein the transducer comprises a second electrical conductor which is electrically conductive connected with the metal electrode.

9. A transducer according to claim 1 , wherein the transducer is associated with a transducer block comprising a top side and a bottom side wherein at least a portion of the second outer-surface of the transducer is attached to a first portion of the bottom side of the transducer block such that the first portion of the bottom side of the transducer block and the portion of the second outer surface of the transducer face each other.

10. The transducer according to claim 9 , wherein the transducer block comprises a metal electrode which is electrically isolated from the first metal plate wherein an outer surface of the metal electrode and the first outer surface of the first metal plate or the piezoelectric element lie at least substantially in a same flat plane wherein the electrode is formed by a second portion of the bottom side of the transducer block which is not covered by the second outer surface of the transducer.

11. The transducer according to claim 9 , wherein at least the portion of the second outer surface of the transducer which is attached to the bottom side of the transducer block is covered by the insulation covering.

12. The transducer according to claim 9 , wherein the transducer block comprises a bore extending from the top side of the transducer block towards the transducer wherein the first electrical conductor extends through the bore and wherein optionally a second electrical conductor is electrically conductive connected to the metal electrode and extends through the bore or outside the transducer block wherein optionally the second electrical conductor is electrically conductive connected to an outside of the transducer block and thereby with the metal electrode and extends outside the transducer block.

13. The transducer according to claim 12 , wherein the bore comprises a widened portion near an end of the bore at the bottom side of the transducer block.

14. The transducer according to claim 13 , wherein at least a portion of the second outer surface of the transducer which is not covered by the insulation covering partially extends over the widened portion of the bore.

15. The transducer according to claim 12 wherein the transducer block is provided with an electrical connector, and wherein optionally the second conductor is electrically conductive connected with the connector.

16. The transducer according to claim 11 , wherein the portion of the insulating covering which covers the portion of the second outer surface of the transducer is attached to and covers the first portion of the bottom side of the transducer block.

17. The transducer of claim 10 wherein the first portion of the bottom side of the transducer block and the second portion of the bottom side of the transducer block which forms the electrode do not overlap each other and together form the bottom side of the transducer block.

18. The transducer according to claim 9 , wherein a portion of the insulating covering which covers the first portion of the first outer surface of the transducer extends to and covers at least a portion of at least one sidewall of the transducer block.

19. The transducer of any preceding claim 9 wherein the top side of the transducer block is provided with a recess extending over a full width of the transducer block wherein a strip can be accommodated for attaching the transducer block to the object such that the piezoelectric ceramics element lies directly against an outer surface of the object without any intermediate medium so that there is a dry coupling between the piezoelectric ceramics element and the surface of the object wherein the strip extends around a circumference of the object.

20. The transducer of any preceding claim 9 wherein the top side of the transducer block is provided with an irregular or grooved surface to reduce internal ultrasonic reflections.

21. An assembly of a transducer block comprising:

a first outer surface;

a second outer surface lying opposite to each other wherein a piezoelectric ceramics element is attached to the first outer surface wherein the dimensions of the first outer surface and the piezoelectric ceramics element are such that a first portion of the first outer surface is not covered with the piezoelectric ceramics element;

wherein a first electrical conductor is electrically conductive attached to at least one of a first portion of the second outer surface and the first portion of the first outer surface wherein the first portion of the first outer surface and the first portion of the second outer surface lie opposite each other and have about the same dimensions and positions in a plane wherein a metal plate extends;

wherein at least a portion of an insulation covering covers the first portion of the first outer surface so that the piezoelectric ceramics element is arranged to be directly dry coupled to a surface of an object to be inspected by means of the transducer;

wherein the transducer is associated with a transducer block comprising a top side and a bottom side wherein at least a portion of the second outer surface of the transducer is attached to a first portion of the bottom side of the transducer block such that the first portion of the bottom side of the transducer block and the portion of the second outer surface of the transducer face each other; and

wherein the transducer block and a position block are detachably connected to each other wherein an outer surface of the piezoelectric ceramics element lies above an upper portion of a bottom surface of the positioning block lying adjacent the transducer block and wherein the transducer block and the positioning block are movable relative to each other in a direction perpendicular to the bottom side of the transducer block.

22. The assembly according to claim 21 wherein the positioning block is provided with a recess extending over a full width of the positioning block at a top side of the positioning block for accommodating a strip.