Capacitive touch sensitive display with dummy pads and without rear shielding layer

• US 8,502,794 B2
• Filed: 08/17/2011
• Issued: 08/06/2013
• Est. Priority Date: 12/30/2010
• Status: Active Grant

• Current Assignee: eGalax_eMPIA Technology Inc.
• Original Assignee: eGalax_eMPIA Technology Inc.
• Inventors: Chang, Chin-Fu
• Primary Examiner(s): CERULLO, LILIANA P
• Application Number:
  US13/211,591
• Publication Number:
  US 20120169649A1
• Time in Patent Office: 720 Days
• Field of Search: 345173-184, 178 1801- 2004
• US Class Current: 345/173
• CPC Class Codes: G06F 2203/04103 Manufacturing, i.e. details related to manufacturing processes specially suited for touch sensitive devices
• CPC Class Codes: G06F 2203/04104 Multi-touch detection in digitiser, i.e. details about the simultaneous detection of a plurality of touching locations, e.g. multiple fingers or pen and finger
• CPC Class Codes: G06F 2203/04107 Shielding in digitiser, i.e. guard or shielding arrangements, mostly for capacitive touchscreens, e.g. driven shields, driven grounds
• 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 3/04166 Details of scanning methods, e.g. sampling time, grouping of sub areas or time sharing with display driving Synchronisation with the driving of the display or the backlighting unit to avoid interferences generated internally G06F3/04184
• CPC Class Codes: G06F 3/0418 for error correction or compensation, e.g. based on parallax, calibration or alignment
• 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 3/0447 Position sensing using the local deformation of sensor cells

Abstract

The present invention provides a mutual capacitive multi-touch screen. The conductive strip pattern allows that, when a touch range of each external conductive object on the mutual capacitive multi-touch screen is larger than a predetermined condition, capacitive coupling between each external conductive object and first conductive strip is greater than capacitive coupling between each external conductive object and second conductive strip, such that the proportion of a driving signal flowing out of the first conductive strip via at least one first external conductive object in the external conductive objects and into the second conductive strip via at least one second external conductive object in the external conductive objects decreases as the number of second external conductive objects increases.

Claims

1. A signal detection method for a capacitive touch sensitive display, comprising:

providing said capacitive touch sensitive display, including;

a double ITO (DITO) structure comprising;

a first layer, comprising a plurality of exposed driving conductive strips which receive a driving signal during mutual capacitive detection;

a second layer, comprising a plurality of exposed sensing conductive strips that provide a plurality of mutual capacitive coupling signals during mutual capacitive detection, wherein each of said plurality of sensing conductive strips includes an opening, wherein said opening includes a dummy conductive pad that is on the same layer with said opening and is made of the same material with said driving and sensing conductive strips;

an insulating layer disposed between said first layer and said second layer;

wherein said first layer is closer to an external conductive object than said sensing layer; and

wherein said plurality of driving conductive strips intersect with said plurality of sensing conductive strips;

a display, wherein said DITO structure is directly disposed thereon;

sending said driving signal to a first driving conductive strip of said plurality of driving conductive strips continuously;

generating a sensing information based on said mutual capacitive coupling signals provided by said plurality of sensing conductive strips each time when said driving signal is sent to said first driving conductive strip, wherein said sensing information is generated by calculating a plurality of differential values, each differential value is defined as a difference between a pair of sensing conductive strips;

wherein when a touch area of an external conductive object is larger than a predetermined area or width, capacitance between said external conductive object and said plurality of driving conductive strips is greater than capacitance between said external conductive object and said plurality of sensing conductive strips.

2. The detection method according to claim 1, wherein an exposed area of said plurality of driving conductive strips is greater than an exposed area of said plurality of sensing conductive strips.

3. The detection method according to claim 1, wherein a periphery of said DITO structure is fixed to said display, and a portion of said DITO structure not fixed to said display deforms under pressure, wherein said sensing information is generated by further calculating a plurality of dual differential values, each dual differential value is defined as a difference between a pair of said differential values.

4. The detection method according to claim 1, wherein two zero-crossings in said sensing information corresponds to a touch or proximity of an external conductive object and a zero-crossing is between a positive value and a negative value.

5. The detection method according to claim 1, wherein an exposed area of said plurality of driving conductive strips covered by said touch area is greater than an exposed area of said plurality of sensing conductive strips covered by said touch area.

6. The detection method according to claim 1, wherein driving conductive strips not receiving said driving signal are provided with a DC potential.

7. A signal detection method for a capacitive touch sensitive display according to claim 1, further comprising:

simultaneously and continuously sending said driving signal to a second driving conductive strip and said first driving conductive strip of said plurality of driving conductive strips; and

generating a sensing information based on said mutual capacitive coupling signals provided by said plurality of sensing conductive strips each time when said driving signal is sent to said first driving conductive strip and said second driving conductive strip simultaneously, wherein said sensing information is generated by calculating a plurality of differential values, each differential value is defined as a difference between a pair of sensing conductive strips.

8. A capacitive touch sensitive display, comprising:

a double ITO (DITO) structure comprising;

a first layer, comprising a plurality of exposed driving conductive strips which receive a driving signal during mutual capacitive detection;

a second layer, comprising a plurality of exposed sensing conductive strips that provide a plurality of mutual capacitive coupling signals during mutual capacitive detection, wherein each of said plurality of sensing conductive strips includes an opening, wherein said opening includes a dummy conductive pad that is on the same layer with said opening and is made of the same material with said driving and sensing conductive strips;

an insulating layer disposed between said first layer and said second layer; and

an insulating surface layer disposed on said first layer to receive approaching or touching of at least one external conductive object;

wherein said first layer is closer to an external conductive object than said second layer; and

wherein said plurality of driving conductive strips intersect with said plurality of sensing conductive strips;

a display, wherein said DITO structure is directly disposed thereon;

wherein when a touch area of each external conductive object on said capacitive touch sensitive display is larger than a predetermined area or width, capacitance between each external conductive object and said plurality of driving conductive strips is greater than capacitance between each external conductive object and said plurality of sensing conductive strips.

9. The capacitive touch sensitive display according to claim 8, wherein an exposed area of said plurality of driving conductive strips covered by said touch area is greater than an exposed area of said plurality of sensing conductive strips covered by said touch area.

10. The capacitive touch sensitive display according to claim 8, wherein an exposed area of said plurality of driving conductive strips is greater than an exposed area of said plurality of sensing conductive strips.

11. The capacitive touch sensitive display according to claim 8, further comprising a control circuit for performing the following operations:

a first driving conductive strip of said plurality of driving conductive strips continuously; and

generating a sensing information based on said mutual capacitive coupling signals provided by said plurality of sensing conductive strips each time when said driving signal is sent to said first driving conductive strip, wherein said sensing information is generated by calculating a plurality of differential values, each differential value is defined as a difference between a pair of sensing conductive strips;

wherein is fixed to said display.

12. The capacitive touch sensitive display according to claim 11, wherein the periphery of said DITO structure is fixed to said display, and a portion of said DITO structure not fixed to said display deforms under pressure, wherein said sensing information is generated by further calculating a plurality of dual differential values, each dual differential value is defined as a difference between a pair of said differential values.

13. The capacitive touch screen according to claim 8, wherein driving conductive strips not provided with said driving signal are provided with a DC potential.

14. The capacitive touch sensitive display according to claim 11, wherein the control circuit further comprising performing the following operations:

simultaneously and continuously sending said driving signal to a second driving conductive strip and said first driving conductive strip of said plurality of driving conductive strips; and

generating a sensing information based on said mutual capacitive coupling signals provided by said plurality of sensing conductive strips each time when said driving signal is sent to said first driving conductive strip and said second driving conductive strip simultaneously, wherein said sensing information is generated by calculating a plurality of differential values, each differential value is defined as a difference between a pair of sensing conductive strips.

15. A capacitive touch sensitive display, comprising:

a double ITO (DITO) structure comprising;

a first layer, comprising a plurality of exposed driving conductive strips which receive a driving signal during mutual capacitive detection;

a second layer, comprising a plurality of exposed sensing conductive strips that provide a plurality of mutual capacitive coupling signals during mutual capacitive detection, wherein each of said plurality of sensing conductive strips includes an opening, wherein said opening includes a dummy conductive pad that is on the same layer with said opening and is made of the same material with said driving and sensing conductive strips;

a display, wherein said DITO structure is directly disposed thereon;

wherein when a touch area of each external conductive object on said capacitive touch sensitive display is larger than a predetermined area or width, capacitance between each external conductive object and said plurality of driving conductive strips is greater than capacitance between each external conductive object and said plurality of sensing conductive strips.

16. The capacitive touch sensitive display according to claim 15, wherein an exposed area of said plurality of driving conductive strips covered by said touch range area is greater than an exposed area of said plurality of sensing conductive strips covered by said touch area.

17. The capacitive touch sensitive display according to claim 15, wherein an exposed area of the driving conductive strips is greater than an exposed area of said sensing second conductive strips.

18. The capacitive touch sensitive display according to claim 15, further comprising a control circuit for performing the following operations:

sending said driving signal to a first driving conductive strip of said plurality of driving conductive strips continuously; and

generating a sensing information based on said mutual capacitive coupling signals provided by said plurality of sensing conductive strips each time when said driving signal being sent to said first conductive strip, wherein said sensing information is generated by calculating a plurality of differential values, each differential value is defined as a difference between a pair of sensing conductive strips.

19. The capacitive touch sensitive display according to claim 18, wherein the periphery of said DITO structure is fixed to said display, and a portion of said DITO structure not fixed to said display deforms under pressure, wherein said sensing information is generated by further calculating a plurality of dual differential values, each dual differential value is defined as a difference between a pair of said differential values.

20. The capacitive touch screen according to claim 15, wherein driving conductive strips not provided with said driving signal are provided with a DC potential.

21. The capacitive touch sensitive display according to claim 18, wherein the control circuit further comprising performing the following operations:

simultaneously and continuously sending said driving signal to a second driving conductive strip and said first driving conductive strip of said plurality of driving conductive strips; and

generating a sensing information based on said mutual capacitive coupling signals provided by said plurality of sensing conductive strips each time when said driving signal is sent to said first driving conductive strip and said second driving conductive strip simultaneously, wherein said sensing information is generated by calculating a plurality of differential values, each differential value is defined as a difference between a pair of sensing conductive strips.