Methods and apparatus employing apparent resonant properties of thin conducting materials
First Claim
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1. Apparatus for detecting electrically conductive material comprising:
- a thin layer of conductive material capable of exhibiting spontaneous resonance wherein spontaneous resonance is defined as a characteristic enabling said thin layer to emulate a passive resonant circuit and absorb energy from an appropriately tuned oscillating circuit, said thin layer of conductive material defining a first surface and having a thickness which is less than the skin effect depth of said layer at a predetermined frequency; and
oscillator means having a resonant tank circuit including capacitor means and coil means, said coil means having a plurality of turns defining a second surface substantially parallel to said first surface, said oscillator means having a frequency in relation to the thickness of said thin layer causing a marked reduction in the amplitude of oscillations of said oscillator means when said thin layer of conductive material is placed proximate to said coil in the absence of other conductive material.
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Abstract
Methods and apparatus for sensing, switching and modulating relying upon apparent resonant properties of thin conductive materials are provided in accordance with the teachings of the present invention. According to the present invention, an output of an oscillating circuit is selectively varied as a function of the relationship between a coil within the oscillating circuit, a thin conductive member and the apparent resonant condition of the thin conductive member to achieve appropriate sensing, switching and modulating conditions.
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Citations
62 Claims
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1. Apparatus for detecting electrically conductive material comprising:
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a thin layer of conductive material capable of exhibiting spontaneous resonance wherein spontaneous resonance is defined as a characteristic enabling said thin layer to emulate a passive resonant circuit and absorb energy from an appropriately tuned oscillating circuit, said thin layer of conductive material defining a first surface and having a thickness which is less than the skin effect depth of said layer at a predetermined frequency; and oscillator means having a resonant tank circuit including capacitor means and coil means, said coil means having a plurality of turns defining a second surface substantially parallel to said first surface, said oscillator means having a frequency in relation to the thickness of said thin layer causing a marked reduction in the amplitude of oscillations of said oscillator means when said thin layer of conductive material is placed proximate to said coil in the absence of other conductive material. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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27. Apparatus for sensing electrically conductive material comprising:
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a thin layer of conductive material capable of exhibiting spontaneous resonance and having a thickness which is less than the skin effect depth of said layer at a predetermined frequency wherein spontaneous resonance is defined as a characteristic enabling said thin layer to emulate a passive resonant circuit and absorb energy from an appropriately tuned oscillating circuit; and oscillator means having inductor means therein, said inductor means being disposed to induce a field within said layer of conductive material, said oscillator means having a frequency in relation to the thickness of said thin layer of conductive material to cause spontaneous resonance to occur when said thin layer of conductive material is adjacent to said inductor means and no other conductive material is adjacent to said thin layer of conductive material and to cause the effect of spontaneous resonance to be negated when other conductive material is adjacent to said thin layer of conductive material. - View Dependent Claims (28, 29, 30, 31, 32, 33, 34, 35)
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36. Apparatus for sensing electrically conductive material comprising:
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a thin layer of conductive material capable of exhibiting spontaneous resonance and having a thickness which is less than the skin effect depth of said layer at a predetermined frequency wherein spontaneous resonance is defined as a characteristic enabling said thin layer to emulate a passive resonant circuit and absorb energy from an appropriately tuned oscillating circuit; and oscillator means having coil means therein, said coil means being disposed to induce a charge pattern corresponding substantially to a mirror image of said coil means in said thin layer of conductive material, said oscillator means having a frequency in relation to the thickness of said thin layer of conductive material to cause said mirror image to be induced and to cause spontaneous resonance to occur when said thin layer of conductive material is adjacent to said coil means and no other conductive material is adjacent to said thin layer of conductive material and to cause spontaneous resonance to be inhibited when other conductive material is in proximity to said thin layer of conductive material. - View Dependent Claims (37, 38, 39, 40, 41, 42, 43)
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44. Apparatus for sensing electrically conductive material comprising:
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a thin layer of conductive material capable of exhibiting spontaneous resonance and having a thickness which is less than the skin effect depth of said layer at a predetermined frequency wherein spontaneous resonance is defined as a characteristic enabling said thin layer to emulate a passive resonant circuit and absorb energy from an appropriately tuned oscillating circuit; and oscillator means having a resonant circuit including inductor means, said inductor means taking the form of a coil formed as a single layer defining a surface, said oscillator means having a resonant frequency selected in relation to the thickness of said thin layer for causing spontaneous resonance to occur when said thin layer is disposed proximate to said coil. - View Dependent Claims (45, 46, 47, 48, 49, 50, 51)
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52. Apparatus for detecting electrically conductive material comprising:
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a thin layer of conductive material capable of exhibiting spontaneous resonance and having a thickness which is less than the skin effect depth of said layer at a predetermined frequency wherein spontaneous resonance is defined as a characteristic enabling said thin layer to emulate a passive resonant circuit and absorb energy from an appropriately tuned oscillating circuit; and oscillator means having a resonant circuit including coil means, said coil means defining a surface, said surface defined by said coil means being disposed proximate to and substantially parallel with said thin layer of conductive material, said oscillator means having a resonant frequency selected in relation to the thickness of said thin layer to cause the magnitude of oscillations produced by said oscillator means to be markedly reduced in the absence of other conductive material adjacent to said thin layer of conductive material and to be of substantially full magnitude when other conductive material is adjacent to said thin layer of conductive material. - View Dependent Claims (53)
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54. A method of sensing electrically conductive material comprising the steps of:
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disposing a thin layer of electrically conductive material having a thickness which is less than the skin effect depth of said layer at a predetermined frequency in the field of an inductive coil of an oscillator; operating said oscillator at a frequency in relation to the thickness of said thin layer of electrically conductive material to cause said inductive coil to establish an induced tuned circuit in said thin layer of electrically conductive material and to establish therewith an associated induced lectromagnetic field; and monitoring the presence of said induced tune circuit in said thin layer of electrically conductive material to determine the presence of electrically conductive material in said area.
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55. Apparatus for detecting electrically conductive material comprising:
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a thin layer of conductive material having a thickness which is less than the skin effect depth of said layer at a predetermined frequency; and oscillator means having a resonant circuit including coil means, said coil means defining a surface, said surface defined by said coil means being disposed proximate to said thin layer of conductive material, said oscillator means having a resonant frequency selected in relation to the thickness of said thin layer to cause the magnitude of oscillations produced by said oscillator means to be markedly reduced in the absence of other conductive material adjacent to said thin layer of conductive material and to be of substantially full magnitude when other conductive material is adjacent to said thin layer of conductive material. - View Dependent Claims (56, 57)
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58. A method of sensing electrically conductive material comprising the steps of:
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selecting a thin layer of conductive material capable of exhibiting spontaneous resonance and having a thickness which is less than the skin effect depth of said layer at a predetermined frequency wherein spontaneous resonance is defined as a characteristic enabling said thin layer to emulate a passive resonant circuit and absorb energy from an appropriately tuned oscillating circuit; employing a coil having a plurality of turns forming a surface in a resonant tank circuit of an oscillator; and operating said oscillator at a frequency in relation to the thickness of said thin layer to cause spontaneous resonance to occur when said thin layer of conductive material is proximate to and substantially parallel with said surface formed by said plurality of turns and no other conductive material is adjacent to said thin layer of conductive material.
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59. A method of sensing electrically conductive material comprising the steps of:
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disposing a thin layer of conductive material adjacent to a path of translation of electrically conductive material to be sensed, said thin layer of conductive material forming a first surface substantially parallel to said path of translation and having a thickness which is less than the skin effect depth of said layer at a predetermined frequency; placing a coil having a plurality of turns forming a second surface proximate to said thin layer of conductive material in such manner that said first and second surfaces are substantially parallel and each of said plurality of turns in said coil is equidistant from said first surface; and connecting said coil in the tank circuit of an oscillator having a frequency which in relation to the thickness of said thin layer of conductive material will cause a marked reduction in the magnitude of oscillations produced by said oscillator in the absence of other conductive material adjacent to said thin layer of conductive material and to be of substantially full magnitude when other conductive material is adjacent to said thin layer of conductive material.
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60. A method of sensing electrically conductive material comprising the steps of:
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selecting a thin layer of conductive material capable of forming a charge pattern corresponding substantially to a mirror image of a coil therein, said thin layer having a thickness which is less than the skin effect depth of said layer at a predetermined frequency; connecting a coil having a plurality of turns formed as a surface in the tank circuit of an oscillator having a frequency which in relation to the thickness of said thin layer of conductive material will inhibit electron flow between charge pattern images formed in said thin layer of conductive material; placing said thin layer of conductive material proximate to and in parallel with said surface formed by said coil; and monitoring the operation of said oscillator to determine the presence of electrically conductive material.
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61. A method of detecting electrically conductive material comprising the steps of:
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disposing a thin layer of conductive material capable of exhibiting spontaneous resonance adjacent to a path of translation of electrically conductive material to be sensed wherein spontaneous resonance is defined as a characteristic enabling said thin layer to emulate a passive resonant circuit and absorb energy from an appropriately tuned oscillating circuit, said thin layer of conductive material forming a first surface substantially parallel to said path of translation and having a thickness which is less than the skin effect depth of said layer at a predetermined frequency; placing a coil having a plurality of turns forming a second surface proximate to said thin layer of conductive material in such manner that said first and second surfaces are substantially parallel and each of said plurality of turns in said coil is equidistant from said first surface; and connecting said coil in the tank circuit of an oscillator having a frequency which in relation to the thickness of said thin layer of conductive material will cause spontaneous resonance to occur in said thin layer of conductive material in the absence of electrically conductive material to be sensed.
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62. Apparatus for sensing electrically conductive material comprising:
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a plurality of thin layers of electrically conductive material disposed about a path to be translated by electrically conductive material to be sensed, each of said plurality of thin layers having a thickness which is less than the skin effect depth of said layers at a predetermined frequency; a plurality of coil means, each coil means defining a surface and being associated with and disposed substantially in parallel to a particular one of said plurality of thin layers of electrically conductive material such that each of said plurality of thin layers of electrically conductive material has one of said plurality of coil means associated therewith; a plurality of oscillator means, each of said plurality of oscillator means having a resonant circuit including one of said plurality of coil means, each of said plurality of oscillator means having a resonant frequency selected in relation to the thickness of a thin layer of conductive material associated with said one of said plurality of coil means in the resonant circuit thereof; and means for monitoring said plurality of oscillator means for sensing electrically conductive material.
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Specification