Triangular piezoelectric transducer for recording video information

Abstract

A cutterhead assembly suitable for forming a topographic signal-representative pattern in a recording medium such as a disc is constructed with non-parallel external surfaces so as to provide a response relatively free of undesired resonant modes over a relatively wide frequency range. The cutterhead includes a cutting stylus supported in a stylus mount. The stylus mount and therefore the stylus are driven by a piezoelectric element which is mounted on a supporting pedestal. A resilient mounting means is utilized to fasten the supporting pedestal to a mounting bracket.

What is claimed is: 
     
       1. Apparatus for providing displacement of a cutting stylus in response to electrical signals and adapted for mounting to a bracket comprising: .Iadd.(1) .Iaddend.a pedestal having first and second opposing sides of different surface area;   .Iadd.(2) .Iaddend.a cutting stylus;   .[.a stylus mount having a base region and adapted for receiving said cutting stylus;.].   .Iadd.(3) .Iaddend.a piezoelectric element having first and second opposing sides, said first side of said .Iadd.piezoelectric .Iaddend.element adjacent to and rigidly coupled to a first side of said pedestal  .[.and said second side of said element adjacent to and rigidly coupled to said base region of said stylus mount,.].;   .Iadd.(4) means for rigidly coupling said cutting stylus to said second side of said piezoelectric element; .Iaddend.   said pedestal, .Iadd.said .Iaddend.piezoelectric element, and .[.stylus mount.]. .Iadd.said coupling means .Iaddend.forming a structure having all external surfaces disposed anti-parallel to each other;   .Iadd.(5) .Iaddend.means for providing electrical signals to said piezoelectric element; and   .Iadd.(6) .Iaddend.means for mounting said second side of said pedestal on said bracket.   
     
     
       2. Apparatus according to claim 1 wherein: said pedestal is made of material having a relatively high Young's modulus and a relatively high density.   
     
     
       3. Apparatus according to claim 2 wherein: said pedestal of material having a high Young's modulus and high density is selected from the group of materials consisting of steel and tungsten.   
     
     
       4. Apparatus according to claim 1 .Iadd.wherein said rigid coupling means comprises a stylus mount having a base region and adapted for receiving said cutting stylus, wherein said second side of said element is adjacent to and rigidly coupled to said base region of said stylus mount, and .Iaddend.wherein: said stylus mount is made of material having a relatively high Young's modulus and a relatively low density.   
     
     
       5. Apparatus according to claim 4 wherein: said stylus mount is selected from the group of materials having a high Young's modulus and low density consisting of aluminum, magnesium, beryllium and sapphire.   
     
     
       6. Apparatus according to claim 1 .Iadd.wherein said rigid coupling means comprising a stylus mount having a base region and adapted for receiving said cutting stylus, wherein said second side of said element is adjacent to and rigidly coupled to said base region of said stylus mount, and .Iaddend.wherein: said pedestal and .Iadd.said .Iaddend.stylus mount are truncated triangular pyramids and said piezoelectric element is triangular in cross-section, with the pyramidal shapes tapering toward said cutting stylus from said bracket.   
     
     
       7. A video disc cutterhead according to claim 6 wherein: said piezoelectric element is a truncated triangular pyramid tapering towards said stylus.   
     
     
       8. A video disc cutterhead according to claim 1 .Iadd.wherein said rigid coupling means comprises a stylus mount having a base region and adapted for receiving said cutting stylus, wherein said second side of said element is adjacent to and rigidly coupled to said base region of said stylus mount, and .Iaddend.wherein: said pedestal, .Iadd.said .Iaddend.stylus mount and .Iadd.said .Iaddend.piezoelectric element are truncated conicals, with the conical shapes tapering towards said stylus.   
     
     
       9. Apparatus according to claim 1 .Iadd.wherein said rigid coupling means comprises a stylus mount having a base region and adapted for receiving said cutting stylus, wherein said second side of said element is adjacent to and rigidly coupled to said base region of said stylus mount, and .Iaddend.wherein: said means for providing electrical signals to said piezoelectric element includes first and second wires respectively coupled to said pedestal and said stylus mount; and conductive cementing material interposed between adjacent sides of said piezoelectric element and said pedestal and said stylus mount.   
     
     
       10. Apparatus according to claim 1 .Iadd.wherein said rigid coupling means comprises a stylus mount having a base region and adapted for receiving said cutting stylus, wherein said second side of said element is adjacent to and rigidly coupled to said base region of said stylus mount, and .Iaddend.wherein: said means for mounting said second side of said pedestal on said bracket includes damping material interposed between said second side and said bracket, said damping material adapted for adhesively coupling said pedestal to said bracket.   
     
     
       11. Apparatus according to claim 10 wherein: said pedestal and .Iadd.said .Iaddend.stylus mount are truncated triangular pyramids and said piezoelectric element is triangular in cross-section, with the pyramidal shapes tapering toward said cutting stylus from said bracket.   
     
     
       12. Apparatus according to claim 11 wherein: said stylus mount is made of material having a relatively high Young's modulus and a relatively low density.   
     
     
       13. Apparatus according to claim 12 wherein: said pedestal is made of material having a relativey high Young's modulus and a relatively high density.   
     
     
       14. Apparatus according to claim 13 wherein: said means for providing electrical signals to said piezoelectric element includes first and second wires respectively coupled to said pedestal and said stylus mount; and conductive cementing material interposed between adjacent sides of said piezoelectric element and said pedestal and said stylus mount.