Position sensor

• US 6,888,538 B2
• Filed: 03/28/2002
• Issued: 05/03/2005
• Est. Priority Date: 05/14/1994
• Status: Expired due to Fees

• Current Assignee: Synaptics (UK) Ltd. (Synaptics Incorporated)
• Original Assignee: Synaptics (UK) Ltd. (Synaptics Incorporated)
• Inventors: Ely, David T. E., Dames, Andrew N.
• Primary Examiner(s): Lamarre, Greg J.
• Assistant Examiner(s): Alphonse, Fritz
• Application Number:
  US10/108,266
• Publication Number:
  US 20020179339A1
• Time in Patent Office: 1,132 Days
• Field of Search: 345/157, 345/173, 345/179, 178/18.07, 178/18.08, 178/19.04
• US Class Current: 345/173
• CPC Class Codes: G01D 5/2073 by movement of a single coil with respect to two or more coils
• CPC Class Codes: G01D 5/208 using polyphase currents
• CPC Class Codes: G06F 1/1626 with a single-body enclosure integrating a flat display, e.g. Personal Digital Assistants [PDAs]
• CPC Class Codes: G06F 1/1643 the display being associated to a digitizer, e.g. laptops that can be used as penpads details related to the relative motion of the display enclosure with respect to the body enclosure, e.g. to move between laptop and tablet PC configuration G06F1/1615
• CPC Class Codes: G06F 3/03545 Pens or stylus
• CPC Class Codes: G06F 3/041 Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
• CPC Class Codes: G06F 3/046 by electromagnetic means

Abstract

A low cost x-y digitising system is provided for use in consumer electronic devices, such as portable digital assistants, mobile telephones, web browsers and the like. The digitiser includes a resonant stylus, an excitation winding for energising the resonant stylus and a set of sensor windings for sensing the signal generated by the stylus, from which the x-y position of the stylus is determined.

Claims

1. A hand-held portable battery-powered data processing device comprising:

a freely movable stylus comprising an electromagnetic resonator; and

a housing comprising;

a memory for storing data;

a display for displaying data within an X-Y display area to a user;

a user interface via which the user can manipulate the stored data using said stylus;

a main processor operable to receive data from the user interface and to control the operation of the device to effect the desired user manipulation of the stored data; and

a power circuit operable to receive energy front a battery and to provide power to said memory, display, user interface and the main processor;

wherein said user interface comprises;

a base mounted substantially parallel to and overlapping said X-Y display area and carrying;

(i) an excitation winding for receiving an excitation signal and for generating an electromagnetic field to cause said electromagnetic resonator resonate when said stylus is in the vicinity of said base;

(ii) an X sensor winding which extend is substantially over the whole X-Y display area and which is operable to output a signal that varies with the relative X position between the stylus and the X-Y display area when said electro magnetic resonator resonates in the vicinity of said base; and

(iii) one or more Y sensor windings which are arranged substantially over the whole X-Y display area and which are operable to output signals that vary with the relative Y position between the stylus and the X-Y display area when said electromagnetic resonator resonates in the vicinity of said base;

an excitation circuit operable to receive energy from said battery and operable to generate said excitation signal for output to said excitation winding; and

a position processor operable to process the signals from said X and Y sensor windings to provide position information of said stylus relative to said X-Y display area to said main processor.

2. The device according to claim 1, wherein said base is mounted under said display relative to a viewing side of said display.

3. A device according to claim 2, wherein said display is a liquid crystal display and wherein a backlight is provided disposed between said liquid crystal display and said base.

4. A device according to claim 3, wherein an electrostatic screen is provided between said base and said backlight.

5. A device according to claim 4, when said electrostatic screen is formed from a continuous layer of carbon ink.

6. A device according to claim 1, wherein said memory, main processor, power circuit, excitation circuit and position processor are located on a printed circuit board located under said base relative to said display.

7. A device according to claim 6, wherein magnetic screen is provided between said base and said printed circuit board.

8. A device according to claim 7, wherein said magnetic screen comprises spin melt ribbon.

9. A device according to claim 1, wherein said X sensor winding comprises at least two sets of loops which are arranged along the X direction of said X-Y display area, said sets of loops being connected in series and arranged so that signal induced in loops of the same set by common background alternating magnetic field add together and so that the signal induced in the loops of one set by a common background alternating magnetic field oppose the signal induced in the loops of the other set.

10. A device according to claim 9, wherein each set of loops comprises the same number of loops.

11. The device according to claim 9, wherein each set of loops is arranged to enclose substantially the same area.

12. A device according to claim 1, wherein each said one or more Y sensor winding comprises at least two sets of loops which are arranged along the Y direction of said X-Y display area, said sets of loops being connected in series and arranged so that a signal induced in loops of the same set by common background alternating magnetic field add together and so that the signal induced in the loops of one set by a common background alternating magnetic field oppose the signal induced in the loops of the other set.

13. A device according to claim 12, wherein each set of loops comprises the same number of loops.

14. The device according to claim 12, wherein each set of loops is arranged to enclose substantially the same area.

15. The device according to claim 1, wherein said base is a printed circuit board and wherein said windings are formed as conductor tracks on the printed circuit board.

16. An apparatus according to claim 15, wherein said base printed circuit board is a flexible printed circuit board.

17. A device according to claim 15, wherein each said one or more Y sensor winding is arranged on said base so that the output signal therefrom varies substantially sinusoidally with the relative Y position between said stylus and said X-Y display area.

18. A device according to claim 1, wherein X sensor winding is arranged on said base so that the output signal therefrom varies cyclically with the relative X position of the stylus relative to the X-Y display area.

19. A device according to claim 18, wherein said X sensor winding is arranged on said base so that the output signal therefrom varies substantially sinusoidally with the relative X position between said stylus and said X-Y display area.

20. A device according to claim 1, wherein each said one or more Y sensor winding is arranged on said base so that the output signal therefrom varies cyclically with the relative Y position of the stylus relative to the X-Y display area.

21. A device according to claim 1, wherein said excitation winding is formed as a plurality of loops of conductor wound around a periphery of said base.

22. A device according to claim 1, wherein said electromagnetic resonator has an average magnetic center which is located approximately 1/(2π

) of the X or the Y dimension of said X or Y sensor winding from a desired measurement point when a tip of said stylus is touching said display area.

23. A device according to claim 1, wherein said device is a personal digital assistant.

24. A device according to claim 1, wherein said device is a mobile telephone.

25. An apparatus according to claim 1, wherein said stylus comprises:

an elongate housing;

a movable tip mounted at one end of the housing for axial movement between a retracted position and an extended position;

a formerless sensing coil; and

a flux linkage element which extends through the coil; and

wherein said formerless coil and said flux linkage element are mounted for relative movement with the movement of said tip, whereby the inductance of said coil is changed with the movement of said tip.

26. A device according to claim 1, wherein said stylus comprises:

an elongate housing;

a movable tip mounted at one end of the housing for axial movement relative thereto in a first direction from a retracted position to an extended position and in a second, opposite direction from the extended position to the retracted position; and

a movement limiter which is operable to define the extent of movement of the tip relative to the housing between said extended and retracted positions, said movement limiter comprising a first limiting element mounted for movement with the tip and a second movement limiting element fixed to the housing.

27. A device according to claim 1, wherein said excitation winding is provided separate from said X sensor winding.

28. A hand-held portable battery-powered data processing device comprising:

a memory for storing data;

a display for displaying data with an X-Y display area to a user;

a user interface via which the user can manipulate the stored data;

a main processor operable to receive data from the user interface and to control the operation of the device to effect the desired user manipulation of the stored data; and

a power circuit operable to receive energy from a battery and to provide power to said memory, display, user interface and the main processor;

wherein said user interface comprises;

a stylus freely movable over the display by the user and comprising an electromagnetic resonator;

a base mounted substantially parallel to and overlapping said X-Y display area and carrying;

(i) an excitation winding for receiving an excitation signal and for generating an electromagnetic field to cause said electromagnetic resonator to resonate when slid stylus is in the vicinity of said base; and

(ii) X and Y sensor windings which are arranged substantially over the whole X-Y display area and which are operable to output signals that vary with the relative position between the stylus and the X-Y display area when said electromagnetic resonator resonates in the vicinity of said base;

an excitation circuit operable to receive energy from said battery and operable to generate said excitation signal for output to said excitation winding;

a position processor operable to process the signals from said X and Y sensor windings to provide position information of said stylus relative to said X-Y display area to said main processor;

wherein said memory, main processor, power circuit, excitation circuit and position processor are located on a printed circuit board located under said base relative to said display.