EP0537458A1
Expired / Lapsed
EP
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Shielding materials for electromagnetic digitizers
Assignee: International Business Machines Corp
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Filing: 1992-08-31
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Granted: —
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Expires: 2012-08-31
Abstract
Abstract Shielding materials used in electromagnetic digitizers which are packaged in a notebook computer environment. Shielding materials with sufficiently high magnetic permeability to increase the magnetic signal detected by the digitizer sensor grid (22) can be used in such an environment, and can be placed in direct contact with the sensor grid. Aluminum or copper shields (26 or 24) can also be placed in direct contact with the sensor grid to provide the requisite shielding. A combination of conductive and ferrite material can also be used as the conductive base material (29) provides for shielding and a layer of ferrite material (28) increases the magnetic signal and prevents signal attenuation by the conductor.
Inventors
- 👤 Richard Lawrence Garwin
- 👤 Gregory Fraser Russell
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-06 00:38
CPC Classifications
G; G06; G06F; G06F3/00; G06F3/01; G06F3/03; G06F3/041; G06F3/046
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
37 words
An electromagnetic digitizer, comprising: a sensor grid, and a shield plate disposed under said sensor grid, wherein said shield plate comprises a material with sufficiently high magnetic permeability to increase the magnetic signal in said sensor grid.
Claim 2
Dependent Claim
57 words
An electromagnetic digitizer according to claim 1, wherein said sensor grid comprises a multiplicity of wires such that said wires form loops, and wherein said shield plate comprises a conductive material and the product of the magnetic permeability and skin depth of said conductive material is greater than the width of said loops in said sensor grid.
Claim 3
Dependent Claim
57 words
An electromagnetic digitizer according to claim 1, wherein said sensor grid comprises a multiplicity of wires such that said wires form loops, and wherein said shield plate comprises a non-conductive material and the product of the magnetic permeability and the thickness of said non-conductive material is greater than the width of said loops in said sensor grid.
Claim 4
Dependent Claim
29 words
An electromagnetic digitizer according to claim 1, wherein said sensor grid includes a sensor grid substrate; and said shield plate is in direct contact with said sensor grid substrate.
Claim 5
Dependent Claim
70 words
An electromagnetic digitizer, comprising: a sensor grid comprising a multiplicity of wires, a pen comprising a pen coil, and a shield plate disposed under said sensor grid, wherein said shield plate comprises conductive material such that said conductive material is of sufficient thickness and conductivity to prevent penetration of the magnetic field of said pen coil, said shield plate being in close proximity to said wires of said sensor grid.
Claim 6
Dependent Claim
26 words
An electromagnetic digitizer according to claim 5, wherein the separation between said shield plate and said wires of said sensor grid is one millimeter or less.
Claim 7
Dependent Claim
38 words
An electromagnetic digitizer according to claim 5, wherein said sensor grid further comprises a sensor grid substrate and the separation between said shield plate and said wires of said sensor grid is provided by said sensor grid substrate.
Claim 8
Dependent Claim
37 words
An electromagnetic digitizer, comprising: a shield plate disposed under a sensor grid, wherein said shield plate comprises a base material of conductive material with a layer of magnetic material disposed on one side of said base material.
Claim 9
Dependent Claim
17 words
An electromagnetic digitizer according to claim 1 or 4 or 8, wherein said shield plate comprises ferrites.
Claim 10
Dependent Claim
17 words
An electromagnetic digitizer according to claim 5 or 7 or 8, wherein said shield plate comprises copper.
Claim 11
Dependent Claim
15 words
An electromagnetic digitizer according to claim 5 or 8, wherein said shield plate comprises aluminum.
Claim 12
Dependent Claim
35 words
An electromagnetic digitizer, comprising: a shield plate disposed under a sensor grid, wherein said shield plate comprises a material that increases the magnetic signal in said sensor grid and which prevents penetration of magnetic fields.
Claim 13
Dependent Claim
15 words
An electromagnetic digitizer according to claim 12, wherein said shield material comprises a Nickel alloy.
Claim 14
Dependent Claim
17 words
An electromagnetic digitizer according to claim 1 or 4 or 12, wherein said shield plate comprises Mumetal.
References Cited (Backward Citations)
US4497977A
Cited
US4853497A
Cited
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