Touch sensor with linearized response

• US 7,439,963 B2
• Filed: 10/29/2007
• Issued: 10/21/2008
• Est. Priority Date: 12/30/2003
• Status: Expired due to Fees

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Geaghan, Bernard O., Bulat, Bulent, Keefer, Kenneth J.
• Primary Examiner(s): OSORIO, RICARDO
• Application Number:
  US11/927,219
• Publication Number:
  US 20080041641A1
• Time in Patent Office: 358 Days
• Field of Search: 345173-179, 345/156
• US Class Current: 345/173
• 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

Abstract

A field linearization pattern and a touch sensor incorporating same are disclosed. The touch sensor includes a polygonal field linearization pattern disposed around a touch sensitive area. The field linearization pattern includes a first side and a second side that intersect at a first corner. The field linearization pattern further includes an inner row and an outer row of discrete conductive segments. The inner row includes a conductive corner segment at the first corner. The conductive corner segment extends along a portion of the first and second sides of the linearization pattern. The touch sensor further includes electronics configured to detect a location of an input touch applied to the touch sensitive area by generating an electrical current in the linearization pattern. A current flowing from the first side to the second side of the linearization pattern is substantially confined within the linearization pattern.

Claims

1. A touch sensor comprising:

a resistive film covering a touch sensitive area;

at least two polygonal parallel rows surrounding the touch sensitive area including an inner row and an outermost row, the inner row comprising an electrically insulative corner segment in the resistive film at each vertex of the inner row, the outermost row comprising an electrically conductive corner segment disposed on the resistive film at each vertex of the outermost row, each corner segment at a polygon vertex extending along a portion of each of the two edges intersecting at the polygon vertex; and

electrically conductive interconnect lines connected to the conductive corner segments for communicating signals to and from the resistive film for detecting an input touch applied to the touch sensitive area.

2. The touch sensor of claim 1 further comprising electronics configured to detect a location of the input touch by applying an electrical signal to the conductive corner segments via the electrically conductive interconnect lines.

3. The touch sensor of claim 1, wherein the electrically insulative corner segment is formed by a void in the resistive film.

4. The touch sensor of claim 3, wherein the void in the resistive film is formed by ablation or etching.

5. The touch sensor of claim 1, wherein the resistive film includes a metal oxide.

6. The touch sensor of claim 1, wherein the resistive film includes an organic conductor.

7. The touch sensor of claim 1, further comprising a conductive bar connecting segments in adjacent ones of the at least two polygonal parallel rows.

8. The touch sensor of claim 1, wherein conductive segments of the at least two polygonal parallel rows are patterned by screen printing.

9. The touch sensor of claim 1, wherein conductive segments of the at least two polygonal parallel rows are patterned by ink jet printing.

10. A touch sensor comprising:

a resistive film covering a touch sensitive area;

at least one polygonal parallel row of discrete conductive segments disposed on the resistive film and surrounding the touch sensitive area, each edge of each row comprising one or more middle conductive segments disposed between two end conductive segments, end conductive segments at a first vertex in the outermost row being joined at the first vertex to form a conductive corner segment; and

an electrically insulative segment in the resistive film positioned along and oriented inward of the outermost row and proximate the first vertex, the insulating segment partially extending parallel to each of the two sides of the outermost row intersecting at the first vertex.

11. The touch sensor of claim 10 further comprising electronics configured to detect a location of an input touch applied to the touch sensitive area by applying an electrical signal to the conductive corner segment.

12. The touch sensor of claim 10, wherein the electrically insulative segment is formed by a void in the resistive film.

13. The touch sensor of claim 12, wherein the void in the resistive film is formed by ablation or etching.

14. An article comprising:

an electrically resistive film;

two polygonal parallel rows of discrete conductive segments disposed on the resistive film, each row having a conductive corner segment at a same vertex of the polygon, each corner segment extending along a portion of each of the two edges intersecting at the vertex; and

an electrically insulative region formed by omitting a portion of the resistive film between the corner segments of the two rows.

15. A touch sensor comprising the article of claim 14.

16. The article of claim 14, wherein the portion of the resistive film is omitted by ablation or etching.

17. A touch sensor comprising:

a polygonal field linearization pattern disposed on a resistive film around a touch sensitive area and having a first side and a second side intersecting at a first corner, the field linearization pattern having an inner row and an outer row of discrete conductive segments, the inner row having a conductive corner segment at the first corner, the conductive corner segment extending along a portion of the first and second sides of the linearization pattern;

one or more electrically insulative segments in the resistive film disposed so that current flowing around the conductive corner segment from the first side of the linearization pattern to the second side of the linearization pattern is substantially confined within the linearization pattern; and

electronics configured to detect a location of an input touch applied to the touch sensitive area by generating an electrical current in the linearization pattern.

18. The touch sensor of claim 17, wherein the one or more electrically insulative segment are formed by voids in the resistive film.

19. The touch sensor of claim 18, wherein the voids in the resistive film are formed by ablation or etching.