Capacitance sensor, sense method, and manufacturing method

• US 20090184937A1
• Filed: 01/23/2009
• Published: 07/23/2009
• Est. Priority Date: 01/23/2008
• Status: Active Grant

• Current Assignee: Monterey Research, LLC (Vector Capital Corporation)
• Original Assignee: Cypress Semiconductor Corporation (Infineon Technologies AG)
• Inventors: Grivna, Edward L.
• Granted Patent: US 8,405,622 B2
• Time in Patent Office: Days
• US Class Current: 345/173
• CPC Class Codes: G06F 2203/04111 Cross over in capacitive digitiser, i.e. details of structures for connecting electrodes of the sensing pattern where the connections cross each other, e.g. bridge structures comprising an insulating layer, or vias through substrate
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: G06F 3/0443 using a single layer of sensing electrodes
• 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 touch screen may include pixel elements formed in a display substrate that are spaced from one another by an element spacing. A plurality of capacitance sense pads may be formed from a same conductive transparent layer in an array over the display substrate. Each sense pad may be separated from an adjacent sense pad by a pad spacing aligned within element spacing for a uniform light path for the pixel elements.

Claims

1. A capacitance sense assembly, comprising:

a plurality of capacitance sense pads formed from a same conductive transparent layer in an array, each sense pad being separated from selected adjacent sense pad in the first direction by a pad spacing, and being conductively connected to at least one adjacent sense pad by a bridging structure, and

a plurality of alignment features for aligning the pad spacings and bridging structures within pixel element spacings of a display.

2. The capacitance sense assembly of claim 1, further including:

the display having a display surface substantially parallel to the capacitance sense pads comprising a plurality of pixel elements formed in a display substrate, the pixel elements being separated from one another by the pixel element spacings.

3. The capacitance sense assembly of claim 2, further including:

the pixel elements being arranged in an orthogonal array in a x direction and a y direction, the orthogonal array being parallel to the display substrate.

4. The capacitance sense assembly of claim 1, wherein:

the sense pads are arranged in groups along intersecting diagonals to an axis.

5. The capacitance sense assembly of claim 4, wherein:

the intersecting diagonals have a same angle of offset with respect to the axis.

6. The capacitance sense assembly of claim 5, wherein:

the sense pads are arranged in an orthogonal array in the x direction and y direction, and the axis is parallel to the x direction or the y direction.

7. The capacitance sense assembly of claim 5, wherein:

each bridging structure includes

a conductive member that conductively connects a first pair of sense pads and is formed from the same layer as the sense pads, and

a bridging member that conductively connects a second pair of sense pads, and is formed from a different layer than the sense pads; and

each alignment feature includes an intraplanar alignment member and an extraplanar alignment member.

8. A touch screen contact position determination method, comprising:

detecting a change in capacitance at an intersection of at least two groups of sense pads disposed in different diagonal directions with respect to orthogonal directions of a touch screen area; and

translating a point of intersection of the two groups of sense pads into coordinates of the orthogonal directions.

9. The method of claim 8, wherein:

each group of sense pads has a first intercept value and a second intercept value, the first intercept value corresponding to a position where the diagonal of the group of sense pads intersects a first axis of the orthogonal directions, and the second intercept value corresponding to a position where the diagonal of the group of sense pads intersects a second axis of the orthogonal directions, and

translating the point of intersection includes one arithmetic operation between the first intercept values and one arithmetic operation between the second intercept values of the intersecting sense pads groups.

10. The method of claim 9, wherein:

the arithmetic operation includes a subtraction operation.

11. The method of claim 9, wherein:

each first intercept value is a coordinate value that is about one half of the coordinate where the diagonal intersects the first axis, and

each second intercept value is a coordinate value that is about one half of the coordinate where the diagonal intersects the second.

12. The method of claim 8, wherein:

detecting a change in capacitance at an intersection of two groups of sense pads includes

activating each of a plurality of first groups of sense pads, each first group of sense pads having diagonals parallel to one another,

activating each of a plurality of second groups of sense pads, each second group of sense pads having diagonals parallel to one another but not parallel to the diagonals of the first groups of sense pads.

13. The method of claim 8, further including:

transmitting light through the sense pads with a display having pixel elements arranged in an array that extends in the orthogonal directions, the pixel elements comprising pixels having positions indicated by the coordinates of the orthogonal direction.

14. A method, comprising:

forming a touch screen having only a single layer of capacitance sense pads between a touch screen surface for a uniform light transmission path through the touch screen, including

patterning a conductive and transparent film into an array of sense pads by forming gaps in the conductive and transparent film, including at least two alignment features that enable the gaps to be aligned within a predetermined pixel element spacing.

15. The method of claim 14, wherein:

the array of sense pads comprises an orthogonal array with sense pads distributed in a first direction and a second direction that is perpendicular to the first direction; and

patterning the conductive and transparent film includes patterning conductive connections between first sense pads in a third direction different from the first and second directions.

16. The method of claim 15, further including:

forming an insulating layer over at least the conductive connections;

forming a bridge conductive layer over at least the insulating layer; and

patterning the bridge conductive layer to form conductive bridges between second sense pads in a fourth direction different from the first, second, and third directions.

17. The method of claim 14, wherein:

the pixel element spacing includes

areas between arrays of rectangular shapes corresponding pixel element shapes, and

encroachment regions that extend into the rectangular shapes.

18. The method of claim 14, further including:

aligning and bonding the touch screen to a display, so that pixel elements of the display are disposed below only one sense pad with respect to a contact surface of the touch screen.

19. The method of claim 14, wherein:

patterning the conductive and transparent film includes patterning gaps between sense pads in the first direction that are greater than gap between sense pads in the second direction.

20. The method of claim 14, wherein:

patterning the conductive and transparent film includes patterning sense pads having non-rectangular shapes with edges aligned within spacings between pixel elements of the display.