Surface and cordless transducer system

• US 7,868,873 B2
• Filed: 04/01/2005
• Issued: 01/11/2011
• Est. Priority Date: 04/01/2004
• Status: Active Grant

• Current Assignee: Wacom Co Limited (Wacom)
• Original Assignee: Wacom Co Limited (Wacom)
• Inventors: Rodgers, James L., Palay, Steven M.
• Primary Examiner(s): Shalwala; Bipin
• Assistant Examiner(s): SPAR, ILANA L
• Application Number:
  US10/598,460
• Publication Number:
  US 20070177533A1
• Time in Patent Office: 2,111 Days
• Field of Search: 345173-179, 178 1801- 2004
• US Class Current: 345/173
• CPC Class Codes: G06F 3/03545 Pens or stylus
• CPC Class Codes: G06F 3/046 by electromagnetic means

Abstract

A smart surface is disclosed that can stand alone or be contained within a portable computer or other system, for powering and communicating with single or multiple cord-free transducers. Operating or charging power is transmitted by the surface using a carrier signal that is on/off keyed or amplitude modulated with synchronization, clock, enable, address, modes, commands and other pulse width, encoded or digital data. The signal is transmitted to single or multiple cordless smart transducers located on or above the surface, such as pens with multiple pressure sensing and switch capability, pointers, stylus, cursors, pucks, mouse, pawns, implements and similar items. Overlapping resonant inductive circuits are used in the surface to transmit operating power and communicate data to the transducer(s).

Claims

1. A surface and cordless transducer system, the system comprising:

a surface including a position resolving grid, and

a transducer including a power receiving circuit, wherein the power receiving circuit responds to an electromagnetic field radiating from the surface and sends a transmit signal, which is received by the position resolving grid and used to determine a position of the transducer relative to the surface,

wherein the surface further includes a plurality of power transmission coils, which are distinct from the position resolving grid, for radiating the electromagnetic field, the plurality of power transmission coils being overlapping resonant power transmission coils that are configured to generate current multiplication associated with resonance therein; and

wherein the position resolving grid and the plurality of overlapping resonant power transmission coils are arranged coextensively on top of one another to form the surface.

2. The surface and cordless transducer system of claim 1, wherein the plurality of overlapping resonant power transmission coils comprise transmission coils of the resonant inductive type.

3. The surface and cordless transducer system of claim 1, wherein the transducer includes an energy storage portion that is configured to generate and store DC operating power for operating the transducer based on a signal from the power receiving circuit in response to the electromagnetic field radiating from the plurality of overlapping resonant power transmission coils arranged on the surface.

4. The surface and cordless transducer system of claim 1, wherein each of the plurality of overlapping resonant power transmission coils, when inactive, is configured to be tuned to a frequency that is different from its operating frequency so as to minimize an electromagnetic interference between the resonant power transmission coil and the position resolving grid.

5. The surface and cordless transducer system of claim 1, wherein the plurality of overlapping resonant power transmission coils are configured to be squelched when the surface is receiving a transmit signal from the transducer.

6. The surface and cordless transducer system of claim 1, wherein the transducer is configured to perform a predefined modulation on a transmit signal to be sent to the position resolving grid.

7. The surface and cordless transducer system of claim 6, wherein the predefined modulation comprises a time keying modulation or an on/off modulation.

8. The surface and cordless transducer system of claim 1, wherein the transducer includes a low current source that is configured to provide a constant transmit signal level.

9. A method for determining a position of a transducer relative to a surface, wherein the surface includes a position resolving grid and the transducer includes a power receiving circuit, the method comprising:

causing the power receiving circuit to respond to an electromagnetic field radiating from the surface and to send a transmit signal, and

causing the position resolving grid to receive the transmit signal from the transducer to thereby determine a position of the transducer relative to the surface,

wherein the surface further includes a plurality of power transmission coils, which are distinct from the position resolving grid, the plurality of power transmission coils being overlapping resonant power transmission coils that are configured to generate current multiplication associated with resonance therein, and wherein the position resolving grid and the plurality of overlapping resonant power transmission coils are arranged coextensively on top of one another to form the surface, and the method further comprises;

causing the plurality of overlapping resonant power transmission coils to radiate the electromagnetic field.

10. The method of claim 9, wherein the plurality of overlapping resonant power transmission coils comprise transmission coils of the resonant inductive type.

11. The method of claim 9, wherein the transducer includes an energy storage portion, and the method further comprises causing the energy storage portion to generate and store DC operating power for operating the transducer based on a signal from the power receiving circuit in response to the electromagnetic field radiating from the plurality of overlapping resonant power transmission coils.

12. The method of claim 9, further comprising tuning each of the plurality of overlapping resonant power transmission coils, when inactive, to a frequency that is different from its operating frequency so as to minimize an electromagnetic interference between the resonant power transmission coil and the position revolving grid.

13. The method of claim 9, further comprising squelching the plurality of overlapping resonant power transmission coils when the surface is receiving a transmit signal from the transducer.

14. The method of claim 9, further comprising causing the transducer to perform a predefined modulation on a transmit signal to be sent to the position resolving grid.

15. The method of claim 14, wherein the predefined modulation comprises a time keying modulation or an on/off modulation.

16. The method of claim 9, wherein the transducer includes a low current source that is configured to provide a constant transmit signal level.