TRANSDUCER

• US 20100238121A1
• Filed: 07/13/2007
• Published: 09/23/2010
• Est. Priority Date: 07/13/2006
• Status: Active Grant

• Current Assignee: Synaptics (UK) Ltd. (Synaptics Incorporated)
• Original Assignee: Synaptics (UK) Ltd. (Synaptics Incorporated)
• Inventors: Ely, Eliot David Thomas
• Granted Patent: US 8,624,847 B2
• Time in Patent Office: Days
• US Class Current: 345/173
• CPC Class Codes: G06F 2203/04106 Multi-sensing digitiser, i.e. digitiser using at least two different sensing technologies simultaneously or alternatively, e.g. for detecting pen and finger, for saving power or for improving position detection
• CPC Class Codes: G06F 3/0445 using two or more layers of sensing electrodes, e.g. using two layers of electrodes separated by a dielectric layer
• CPC Class Codes: G06F 3/0446 using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes
• CPC Class Codes: G06F 3/046 by electromagnetic means

Abstract

A transducer for a position sensor is described. The transducer comprises a single laminate sensor board carrying a plurality of windings formed by conductors on one or more layers of the sensor board, the windings being arrayed over a first area of the sensor board; and detection circuitry mounted on another layer of the sensor board over a second area of the circuit board and electrically coupled to said windings, said detection circuitry having a first mode of operation in which signals inductively coupled to or from said windings are detected and a second mode of operation in which signals capacitively coupled to or from said windings are detected. The windings and detection circuitry are arranged on the sensor board so that said first and second areas oppose each other. A position sensor incorporating the transducer is also described.

Claims

1. A transducer for use in a position sensor, the transducer comprising a single laminate sensor board carrying:

a plurality of windings formed by conductors on one or more layers of the sensor board, the windings being arrayed over a first area of the sensor board; and

detection circuitry mounted on another layer of the sensor board over a second area of the circuit board and electrically coupled to said windings, said detection circuitry having a first mode of operation in which signals inductively transmitted from or received by said windings are detected and a second mode of operation in which signals capacitively transmitted from or received by said windings are detected,

wherein said windings and said detection circuitry are arranged on said sensor board so that said first and second areas oppose each other.

2. A transducer according to claim 1, wherein said sensor board comprises a conductor plane positioned between the plurality of windings and said detection circuitry to reduce noise when said detection circuitry is operating in said second mode of operation.

3. A transducer according to claim 2, wherein said conductor plane is formed from a plurality of interconnected conductive islands to reduce eddy current noise when said detection circuitry is operating in said first mode of operation.

4. A transducer according to claim 3, wherein said conductor plane is formed from a two dimensional array of interconnected conductive islands.

5. A transducer according to claim 2, wherein said conductor plane is connected to a ground connection of said detection circuitry.

6. A transducer according to claim 1, wherein at least one of said windings comprises conductor traces which form one or more conductive loops for inductive sensing and one or more single ended traces for capacitive sensing.

7. A transducer according to claim 6, wherein each winding comprises conductor traces which form one or more conductive loops for inductive sensing and one or more single ended traces for capacitive sensing.

8. A transducer according to claim 6, wherein said single ended traces are electrically connected at one end to a conductor trace which forms part of said conductive loops and is open circuit at the other end.

9. A transducer according to claim 1, wherein each winding is for sensing position along a measurement path and has a plurality of conductor traces that are distributed along the measurement path.

10. A transducer according to claim 9, wherein the conductor traces of adjacent windings are interleaved with each other along the measurement path.

11. A transducer according to claim 9, wherein the trace width of adjacent traces of the same winding and/or the separation between adjacent traces of the same winding varies along the measurement path.

12. A transducer according to claim 9, wherein the density of conducting material of each winding varies along the measurement path.

13. A transducer according to claim 9, wherein said distributed traces extend substantially perpendicular to said measurement path.

14. A transducer according to claim 9, comprising two groups of windings, the windings in the first group for sensing position along a first measurement path and the windings in the second group for sensing position along a second different measurement path.

15. A transducer according to claim 2, comprising a divided strike ring formed from a plurality of conductor traces on an upper layer of the sensor board which extend around the periphery of the first area and which are electrically connected to said conductor plane.

16. A transducer according to claim 15, wherein said divided strike ring also comprises a plurality of conductor traces on a bottom layer of the sensor board which extend around the periphery of the first area and which are connected to said conductor plane.

17. A transducer according to claim 1, wherein said detection circuitry is carried by a bottom layer of said sensor board.

18. A transducer according to claim 1 wherein said windings are formed from conductor traces on a first, upper, layer of the sensor board and a second, lower, layer of the sensor board and wherein the traces on the second layer have a greater width than the traces on the first layer.

19. A transducer according to claim 1, wherein in said first mode of operation, said detection circuitry is operable to detect and process signals supplied to or received from said windings as a result of inductive coupling of the windings with an electromagnetic user device, to determine the position of the user device relative to the windings.

20. A transducer according to claim 1, wherein in said second mode of operation, said detection circuitry is operable to detect and process signals supplied to or received from said windings as a result of capacitive coupling of the windings with a user'"'"'s finger or the like, to determine the position of the user'"'"'s finger relative to the windings.

21. A transducer according to claim 1, wherein said detection circuitry uses the same processing electronics to process the signals in said first and second modes of operation.

22. A transducer according to claim 1, wherein said detection circuitry is operable, in said first mode of operation, to detect an EMF generated in each winding and is operable, in said second mode of operation, to detect an amount of current or charge supplied to each winding.

24. A position sensor comprising a transducer according to claim 1 and processing circuitry for processing the detected signals and for determining the position of an object relative to the windings of said transducer.

25. A position sensor according to claim 24, wherein said processing circuitry is carried by said sensor board.

23. A transducer for use in a position sensor, the transducer comprising a single laminate sensor board carrying:

a plurality of windings formed by conductors on one or more layers of the sensor board; and

detection circuitry mounted on another layer of the sensor board and positioned under, and electrically coupled to, said windings, said detection circuitry having a first mode of operation in which signals inductively coupled with said windings are detected and a second mode of operation in which signals capacitively coupled with said windings are detected.