David A. Siefer

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Orange, CT, US

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Patents Grantslast 30 patents

Information Patent Grant
Wiegand effect energy generator
- Patent number 6,191,687
- Issue date Feb 20, 2001
- HID Corporation
- David J. Dlugos
- G08 - SIGNALLING
Information Patent Grant
Pressure sensitive stylus having resiliently compressible tip element
- Patent number 5,581,052
- Issue date Dec 3, 1996
- Summagraphics Corporation
- Michael J. Padula
- G06 - COMPUTING CALCULATING COUNTING
Information Patent Grant
Optical accessory for digitizer cursors
- Patent number 5,191,480
- Issue date Mar 2, 1993
- Summagraphics Corporation
- Wayne J. Murray
- G02 - OPTICS
Information Patent Grant
Digitizer tablet with illuminable working surface
- Patent number 5,153,386
- Issue date Oct 6, 1992
- Summagraphics Corporation
- David A. Siefer
- G06 - COMPUTING CALCULATING COUNTING
Information Patent Grant
Digitizer with illuminable working surface
- Patent number 5,028,744
- Issue date Jul 2, 1991
- Summagraphics Corporation
- Alexander M. Purcell
- G06 - COMPUTING CALCULATING COUNTING
Information Patent Grant
Backlit digitizer tablet
- Patent number 4,943,689
- Issue date Jul 24, 1990
- Summagraphics Corporation
- David A. Siefer
- G06 - COMPUTING CALCULATING COUNTING