Sensing film material
First Claim
1. A film thickness sensor for sensing a property of a film of material, the sensor comprising first and second electrodes spaced to define a gap therebetween, the film of material being located within the gap, during use, characterised in that the width of the gap is different at different positions on the electrode members whereby the sensing characteristics of the sensor are different at different positions on the electrode members.
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Accused Products
Abstract
A sensor 30 has first and second electrodes 32A, 32B spaced to define a gap 34 therebetween. The electrodes are formed on a substrate which can be covered with a film of material. The width of the gap 34 is different at different positions on the electrodes 32. This results in a sensing characteristic which can be made substantially linear, without sensitivity varying with film thickness, which arises from the use of a constant gap width. The sensor can be used to detect or measure film or liquid layer thickness, or solid material deposition.
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Citations
18 Claims
- 1. A film thickness sensor for sensing a property of a film of material, the sensor comprising first and second electrodes spaced to define a gap therebetween, the film of material being located within the gap, during use, characterised in that the width of the gap is different at different positions on the electrode members whereby the sensing characteristics of the sensor are different at different positions on the electrode members.
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4. A sensor for sensing a property of a film of material, the sensor comprising first and second electrodes spaced to define a gap therebetween, the film of material being located within the gap, during use, characterised in that the width of the gap is different at different positions on the electrode members whereby the sensing characteristics of the sensor are different at different positions on the electrode members, wherein the width of the gap varies to create a substantially linear output characteristic for the sensor, in response to changes in the property being sensed.
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10. A sensor for sensing a property of a film of material, the sensor comprising first and second electrodes spaced to define a gap therebetween, the film of material being located within the gap, during use, characterised in that the width of the gap is different at different positions on the electrode members whereby the sensing characteristics of the sensor are different at different positions on the electrode members wherein the thickness of at least one electrode is different at different positions on the electrode.
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11. A sensor for sensing a property of a film of material, the sensor comprising first and second electrodes spaced to define a gap therebetween, the film of material being located within the gap, during use, characterised in that the width of the gap is different at different positions on the electrode members whereby the sensing characteristics of the sensor are different at different positions on the electrode members, wherein the electrodes are mounted to be adjustably positioned relative to one another, to allow the gap widths to be changed.
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14. A sensor for sensing a property of a film of material, the sensor comprising first and second electrodes spaced to define a gap therebetween, the film of material being located within the gap, during use, characterised in that the width of the gap is different at different positions on the electrode members whereby the sensing characteristics of the sensor are different at different positions on the electrode members wherein the sensor further comprises control means operable to take measurements from the electrodes, across the gap, and to deduce the film property therefrom wherein the control means is operable at a plurality of frequencies, wherein the or one of the operating frequencies of the voltage source is DC.
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15. A sensor for sensing a property of a film of material, the sensor comprising first and second electrodes spaced to define a gap therebetween, the film of material being located within the gap, during use, characterised in that the width of the gap is different at different positions on the electrode members whereby the sensing characteristics of the sensor are different at different positions on the electrode members wherein the sensor further comprises control means operable to take measurements from the electrodes, across the gap, and to deduce the film property therefrom wherein the control means is operable at a plurality of frequencies, wherein the control means is operable to combine measurements to eliminate at least one frequency-dependent component of the property being sensed.
Specification