Force transducer with screen printed strain gauges
First Claim
1. A force transducer comprising:
- an elongated lever arm having a fixed end and a free end to which an external force is applied;
a sensing element that includes a substrate having a central portion at which the fixed end of the lever arm is attached and at least two substantially planar tab regions that project outwardly from the central portion along first and second orthogonal force detecting axes, the sensing element further including thick film strain gauge material printed onto the substrate in at least first and second locations and including conductive contacts on the substrate that are coupled to the strain gauge material to define a first electrical path and a second electrical path through the strain gauge material and are oriented along the first and second force detecting axes, respectively; and
a support structure that supports the sensing element so that the substrate undergoes localized strain approximately at the junctions of the tab regions and the central portion when the external force is applied to the free end of the lever arm.
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Accused Products
Abstract
A force transducer includes an elongated lever arm attached to a substrate having a central portion and substantially planar tab regions that project outwardly from the central portion along first and second orthogonal force-detecting axes. The substrate undergoes localized strain approximately at the junctions of the tab regions and the central portion when an external force is applied to the free end of the lever arm. A thick film strain gauge material is screen printed directly onto the substrate in at least a first location and a second location and conductive pads on the substrate are electrically coupled to the thick film strain gauge material at each location to define a first strain gauge oriented along the first force detecting axis and a second strain gauge oriented along the second force detecting axis. The lever arm can be of a compliant construction to provide proprioreceptive feedback to a user.
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Citations
48 Claims
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1. A force transducer comprising:
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an elongated lever arm having a fixed end and a free end to which an external force is applied; a sensing element that includes a substrate having a central portion at which the fixed end of the lever arm is attached and at least two substantially planar tab regions that project outwardly from the central portion along first and second orthogonal force detecting axes, the sensing element further including thick film strain gauge material printed onto the substrate in at least first and second locations and including conductive contacts on the substrate that are coupled to the strain gauge material to define a first electrical path and a second electrical path through the strain gauge material and are oriented along the first and second force detecting axes, respectively; and a support structure that supports the sensing element so that the substrate undergoes localized strain approximately at the junctions of the tab regions and the central portion when the external force is applied to the free end of the lever arm. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A force transducer comprising:
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(a) an elongated lever arm having a fixed end and a free end to which an external force is applied; and (b) a sensing element that includes a substrate having a central portion at which the fixed end of the lever arm is attached and at least two substantially planar tab regions that project outwardly from the central portion along first and second orthogonal force detecting axes, thick film strain gauge material printed onto the substrate in at least a first location and a second location such that the strain gauge material bridges the central portion and a respective tab region at each location of the strain gauge material, and conductive contacts on the substrate that are electrically coupled to each location of strain gauge material to define a first strain gauge having an electrical path through the first location oriented along the first force detecting axis and a second strain gauge having an electrical path through the second location oriented along the second force detecting axis; and (c) a support structure that supports the sensing element so that the substrate undergoes localized strain approximately at the junctions of the tab regions and the central portion when the external force is applied to the free end of the lever arm. - View Dependent Claims (15, 16)
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17. A force transducer that receives external forces and generates an electrical signal indicating the components of an external force along at least two force detecting axes when connected to a source of electrical power, the force transducer comprising:
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an elongated lever arm having a fixed end and a free end to which an external force is applied; a substrate having a central portion at which the fixed end of the lever arm is attached and at least two substantially planar tab regions that project outwardly from the central portion along first and second orthogonal force detecting axes so that the substrate undergoes localized strain approximately at the junctions of the tab regions and the central portion when the external force is applied to the free end of the lever arm; thick film strain gauge material printed onto the substrate in at least a first location and a second location such that the strain gauge material at each location bridges the central portion and a tab region across a respective tab region-central portion junction of localized strain; conductive contacts on the substrate that are electrically coupled to the thick film strain gauge material at each location to define a first strain gauge having an electrical path through the first location oriented along the first force detecting axis and a second strain gauge having an electrical path through the second location oriented along the second force detecting axis; a substrate power supply lead connected to the source of electrical power; a substrate x-axis lead connected to the first strain gauge; a substrate y-axis lead connected to the second strain gauge; and a substrate ground lead connected to electrical ground;
wherein;respective electrical signals are produced at the x-axis lead and y-axis lead when an external force is applied to the lever arm.
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18. A force transducer comprising:
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an elongated lever arm having a fixed end and a free end to which an external force is applied; a sensing element that includes a substrate having a central portion at which the fixed end of the lever arm is attached and at least two substantially planar tab regions that project outwardly from the central portion along first and second orthogonal force detecting axes, the sensing element further including at least one strain gauge located substantially at the junction of each tab region and the central portion; and a support structure that supports the sensing element so that the substrate undergoes localized strain approximately at the junctions of the tab regions and the central portion when the external force is applied to the free end of the lever arm;
wherein;each strain gauge includes thick film strain gauge material printed onto the substrate such that the strain gauge material bridges the central portion and a respective tab region of the substrate at each location of the strain gauge material and further includes conductive contacts that are located on the substrate and coupled to the thick film strain gauge material to define an electrical path through the strain gauge material such that an electrical path is defined through each respective strain gauge and is oriented along one of the force detecting axes.
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19. A force transducer comprising:
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an elongated lever arm having a fixed end and a free end to which an external force is applied; a substrate having a central portion at which the fixed end of the lever arm is attached and at least two substantially planar tab regions that project outwardly from the central portion along first and second orthogonal force detecting axes so that the substrate undergoes localized strain approximately at the junctions of the tab regions and the central portion when the external force is applied to the free end of the lever arm; thick film strain gauge material printed onto the substrate in at least a first location and a second location such that the strain gauge material at each location bridges the central portion and a tab region across a respective tab region-central portion junction of localized strain; and conductive contacts on the substrate that are electrically coupled to the thick film strain gauge material at each location to define a first strain gauge having an electrical path through the first location oriented along the first force detecting axis and a second strain gauge having an electrical path through the second location oriented along the second force detecting axis. - View Dependent Claims (20, 21, 22, 23)
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24. A method of producing a force transducer, comprising the steps of:
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providing a substrate having a central portion and at least two substantially planar tab regions that project outwardly from the central portion along first and second orthogonal force detecting axes; printing thick film strain gauge material onto the substrate using screen printing techniques in at least a first location and a second location such that the strain gauge material bridges the central portion and a respective tab region at each location of the strain gauge material; placing conductive contacts on the substrate such that the conductive contacts are electrically coupled to each location of strain gauge material to provide an electrical path through the first location that is oriented along the first force detecting axis, defining a first strain gauge, and to provide an electrical path through the second location oriented along the second force detecting axis, defining a second strain gauge; and attaching an elongated lever arm to the central portion at a fixed end such that when an external force is applied to an opposite, free end of the lever arm the substrate undergoes localized strain approximately at the junctions of the tab regions and the central portion. - View Dependent Claims (25, 26, 27, 28, 29, 30, 31, 32)
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33. A computer system comprising:
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(a) a central processing unit; (b) a display unit; and (c) a keyboard having a plurality of keys and a control actuator having an elongated lever arm having a fixed end and a free end to which an external force is applied, a sensing element that includes a substrate having a central portion at which the fixed end of the lever arm is attached and at least two substantially planar tab regions that project outwardly from the central portion along first and second orthogonal force detecting axes, the sensing element being located such that the lever arm projects upwardly, the sensing element further including thick film strain gauge material printed onto the substrate in at least first and second locations and including conductive contacts on the substrate that are coupled to the strain gauge material to define a first electrical path and a second electrical path through the strain gauge material and are oriented along the first and second force detecting axes, respectively, and a support structure that supports the sensing element so that the substrate undergoes localized strain approximately at the junctions of the tab regions and the central portion when the external force is applied to the free end of the lever arm. - View Dependent Claims (34, 35, 36, 37, 38, 39, 40)
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41. A computer keyboard comprising:
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(a) a keyboard casing; (b) a plurality of keys; and (c) a control actuator having an elongated lever arm having a fixed end and a free end to which an external force is applied, a sensing element that includes a substrate having a central portion at which the fixed end of the lever arm is attached and at least two substantially planar tab regions that project outwardly from the central portion along first and second orthogonal force detecting axes, the sensing element being located in the keyboard casing such that the lever arm projects upwardly, the sensing element further including thick film strain gauge material printed onto the substrate in at least first and second locations and including conductive contacts on the substrate that are coupled to the strain gauge material to define a first electrical path and a second electrical path through the strain gauge material and are oriented along the first and second force detecting axes, respectively, and a support structure that supports the sensing element so that the substrate undergoes localized strain approximately at the junctions of the tab regions and the central portion when the external force is applied to the free end of the lever arm. - View Dependent Claims (42, 43, 44, 45, 46, 47, 48)
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Specification