Variable capacitor and position indicator employing variable capacitor
First Claim
1. A variable capacitor comprising a solid dielectric, a first electrode on the solid dielectric, a second flexible electrode normally spaced by a dielectric gas from a surface of the solid dielectric, the normal spacing between the second electrode and the surface and the flexibility of the second electrode being such that the second electrode (a) is urged into contact with the surface in response to an initial force being applied to the second electrode, (b) has differing contact areas with the surface in response to differing forces greater than the initial force being applied thereto and (c) returns to its normally spaced location from the surface in response to removal of the forces.
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Accused Products
Abstract
A variable capacitor comprises a solid dielectric disc having one electrode disposed on one face thereof. A flexible electrode is selectively urged into contact with a second face of the disc, parallel to the first face. A translatable stem drives the second electrode into contact with the first surface. The variable capacitor is used in an implement which is moved relative to a position detecting tablet. The variable capacitor is part of a tuned circuit having a resonant frequency approximately the same as the frequency of AC energy applied to coils of the position detecting tablet.
113 Citations
45 Claims
- 1. A variable capacitor comprising a solid dielectric, a first electrode on the solid dielectric, a second flexible electrode normally spaced by a dielectric gas from a surface of the solid dielectric, the normal spacing between the second electrode and the surface and the flexibility of the second electrode being such that the second electrode (a) is urged into contact with the surface in response to an initial force being applied to the second electrode, (b) has differing contact areas with the surface in response to differing forces greater than the initial force being applied thereto and (c) returns to its normally spaced location from the surface in response to removal of the forces.
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4. A variable capacitor comprising a solid dielectric, a first electrode on the solid dielectric, a second flexible electrode normally spaced by a dielectric gas from a surface of the solid dielectric, the normal spacing between the second electrode and the surface and the flexibility of the second electrode being such that the second electrode (a) is urged into contact with and has differing contact areas with the surface in response to differing forces being applied thereto and (b) returns to its normally spaced location from the surface in response to removal of the forces, said surface of the solid dielectric being sufficiently smooth and flat that there are virtually no portions between the center and periphery of the contact area region where contact between the solid dielectric surface and the electrode does not exist.
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5. A variable capacitor comprising a solid dielectric, a first electrode on the solid dielectric, a second flexible electrode normally spaced by a dielectric gas from a surface of the solid dielectric, the normal spacing between the second electrode and the surface and the flexibility of the second electrode being such that the second electrode (a) is urged into contact with and has differing contact areas with the surface in response to differing forces being applied thereto and (b) returns to its normally spaced location from the surface in response to removal of the forces, an annular spaced between the dielectric surface and the electrode for establishing the normal spacing, the annular spacer and dielectric surface being arranged so that the electrode is flexed into contact with the dielectric surface through a central opening of the spacer.
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6. A variable capacitor comprising a solid dielectric, a first electrode on the solid dielectric, a second flexible electrode normally spaced by a dielectric gas from a surface of the solid dielectric, the normal spacing between the second electrode and the surface and the flexibility of the second electrode being such that the second electrode (a) is urged into contact with and has differing contact areas with the surface in response to differing forces being applied thereto and (b) returns to its normally spaced location from the surface in response to removal of the forces, a housing in which the solid dielectric, first electrode and second electrode are located and a mechanical drive mechanism for translating the flexible electrode into contact with said dielectric surface, said mechanical drive mechanism including a stem having one end in the housing mechanically coupled to the flexible electrode and a second end extending outside of the housing so that translation of the stem relative to the housing results in translation of the flexible electrode.
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7. A variable capacitor comprising a solid dielectric, a first electrode on the solid dielectric, a second flexible electrode normally spaced by a dielectric gas from a surface of the solid dielectric, the normal spacing between the second electrode and the surface and the flexibility of the second electrode being such that the second electrode (a) is urged into contact with and has differing contact areas with the surface in response to differing forces being applied thereto and (b) returns to its normally spaced location from the surface in response to removal of the forces, a housing having a first cylindrical portion in which the solid dielectric, first electrode and second electrode are located, and a second cylindrical portion nested and friction-fitted with the first cylindrical portion.
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8. A variable capacitor comprising a solid dielectric, a first electrode on the solid dielectric, a second flexible electrode normally spaced by a dielectric gas from a surface of the solid dielectric, the normal spacing between the second electrode and the surface and the flexibility of the second electrode being such that the second electrode (a) is urged into contact with and has differing contact areas with the surface in response to differing forces being applied thereto and (b) returns to its normally spaced location form the surface in response to removal of the forces, a mechanical drive mechanism for translating the flexible electrode into contact with said dielectric surface, said mechanical drive mechanism including an flexible membrane mechanically coupled to the flexible electrode for imparting said forces to the elastic electrode.
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9. A variable capacitor comprising a solid dielectric, a first electrode on the solid dielectric, a second flexible electrode normally spaced by a dielectric gas from a surface of the solid dielectric, the normal spacing between the second electrode and the surface and the flexibility of the second electrode being such that the second electrode 9a) is urged into contact with and has differing contact areas with the surface in response to differing forces being applied thereto and (b) returns to its normally spaced location from the surface in response to removal of the forces, a stem mechanically coupled to the flexible electrode for imparting said forces to the flexible electrode, and a detachable end cap on an end of the portion of the stem for imparting forces imparted along the length of the stem to the flexible electrode.
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10. An implement for supplying position and pressure indications to a tablet on which the implement is adapted to be used, the implement comprising a stem adapted to be displaced in response to pressing thereof against a surface of the tablet, an inductor connected in circuit with a variable capacitor having a variable capacity controlled by displacement of the stem, the variable capacitor including a solid dielectric having a dielectric constant in excess of 100 and fabricated of a material having a tendency to be damaged in response to relatively high voltage being applied to it, the inductor and variable capacitor being in a passive circuit having no power supply terminals connected to it to obviate the tendency of the solid dielectric to be damaged by the application of high voltage, the variable capacitor further including:
- a first electrode on the solid dielectric, a second flexible electrode mechanically coupled to the stem and normally spaced by a dielectric gas from a surface of the solid dielectric, the normal spacing between the second electrode and the surface and the flexibility of the second electrode being such that the second electrode (a) is urged into contact with and has differing contact areas with the surface in response to differing forces being applied thereto by the stem and (b) returns to its normally spaced location from the surface in response to removal of the forces.
- View Dependent Claims (11, 12, 13)
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14. An implement for supplying position and pressure indications to a tablet on which the implement is adapted to be used, the implement comprising an elongated housing having the shape of a pen and a longitudinal axis, the housing including a stem translatable in the direction of the axis by an amount controlled by the pressure exerted by a tip of the stem against a surface of the tablet, the housing including a variable capacitor mechanically coupled to the stem so that capacitance of the capacitor varies in response to translation of the stem in the direction of the axis, said capacitor including:
- a solid dielectric, a first dielectric on the solid dielectric, a second flexible electrode normally spaced by a dielectric gas from a surface of the solid dielectric while no force is applied to the stem, the normal spacing between the second electrode and the surface and the flexibility of the second electrode being such that the second electrode (a) is urged into contact with and has differing contact areas with the surface in response to differing forces being applied thereto by translation of the stem in the direction of the axis and (b) returns to its normally spaced location from the surface in response to removal of the forces.
- View Dependent Claims (15, 16)
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17. An implement for supplying position and pressure indications to a tablet on which the implement is adapted to be used, the implement comprising
an elongated housing, the housing including: -
a stem longitudinally positioned in the housing adapted to be pressed against a surface of the tablet, a translatable member adapted to be translated by varying amounts as a function of the width of a trace, and a variable capacitor having a variable capacity controlled by displacement of the translatable member, the variable capacitor including;
a solid dielectric, a first electrode on the solid dielectric, a second flexible electrode mechanically coupled to the translatable member and normally spaced by a dielectric gas from a surface of the solid dielectric, the normal spacing between the second electrode and the surface and the flexibility of the second electrode being such that the second electrode (a) is urged into contact with and has differing contact areas with the surface in response to differing forces being applied thereto by the translatable member and (b) returns to its normally spaced location from the surface in response to removal of the forces. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43)
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44. A variable capacitor comprising a solid dielectric, a first electrode on the solid dielectric, a second flexible electrode normally spaced by a dielectric gas from a polished surface of the solid dielectric, the normal spacing between the second electrode and the surface and the flexibility of the second electrode being such that the second electrode (a) is urged into contact with and has differing contact areas with the surface in response to differing forces being applied thereto and (b) returns to its normally spaced location from the surface in response to removal of the forces.
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45. A variable capacitor comprising a solid dielectric, a first electrode on the solid dielectric, a second flexible electrode normally spaced by a dielectric gas from a surface of the solid dielectric having a roughness no greater than 0.1 micrometer, the normal spacing between the second electrode and the surface and the flexibility of the second electrode being such that the second electrode (a) is urged into contact with and has differing contact areas with the surface in response to differing forces being applied thereto and (b) returns to its normally spaced location from the surface in response to removal of the forces.
Specification