Capacitive touchscreens for thermostats using smaller capacitors in standby mode

• US 9,207,817 B2
• Filed: 11/07/2012
• Issued: 12/08/2015
• Est. Priority Date: 05/18/2012
• Status: Active Grant

• Current Assignee: Copeland Comfort Control LP (Emerson Electric Company)
• Original Assignee: Emerson Electric Company
• Inventors: Tu, Lihui
• Primary Examiner(s): Ali, Mohammad
• Assistant Examiner(s): Lindsay, Bernard G
• Application Number:
  US13/670,721
• Publication Number:
  US 20130310985A1
• Time in Patent Office: 1,126 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: G05D 23/00 Control of temperature
• CPC Class Codes: G06F 1/3231 Monitoring the presence, absence or movement of users
• CPC Class Codes: G06F 1/3262 Power saving in digitizer or tablet
• 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 3/0445 using two or more layers of sensing electrodes, e.g. using two layers of electrodes separated by a dielectric layer
• CPC Class Codes: H03K 17/962 Capacitive touch switches
• CPC Class Codes: Y02D 10/00 Energy efficient computing, e.g. low power processors, power management or thermal management

Abstract

Exemplary embodiments are disclosed of touchscreen devices for thermostats and other electronic devices. In an exemplary embodiment, a capacitive touchscreen device includes a touchscreen having touch regions. Each touch region is coupled with at least one first capacitor and at least one second capacitor. The second capacitors are connected in parallel and have smaller capacitance than the first capacitors. The capacitive touchscreen device may be configured to be operable in a standby mode in which the second capacitors are charged and an active mode in which the first capacitors are charged.

Claims

1. A capacitive touchscreen device comprising:

a controller;

a plurality of single first capacitors, each having an individual unique input port to the controller;

a plurality of single second capacitors connected in parallel and having a common input port to the controller that is separate from any of the first capacitor input ports, each single second capacitor being different from each single first capacitor and having a smaller individual capacitance than an individual capacitance of any of the single first capacitors; and

a touchscreen including a plurality of mutually isolated touch regions, each said touch region being coupled with one of the single first capacitors and one of the single second capacitors;

whereby the capacitive touchscreen device is configured to be operable in a standby mode in which the single second capacitors are charged and the single first capacitors are not charged to reduce power consumption by the single first capacitors, and to switch to an active mode in which the single first capacitors are charged in response to a detection of a change in capacitance of one or more of the single second capacitors by the controller;

wherein in the standby mode the single second capacitors are charged via the common input port and in the active mode the single first capacitors are charged via each corresponding individual unique input port; and

wherein the controller is configured to scan only the single first capacitors for a change in capacitance during the active mode to determine which touch region is being touched by a user.

2. The capacitive touchscreen device of claim 1, wherein the capacitive touchscreen device is configured to switch from the standby mode in which the single first capacitors are not charged to the active mode in response to a detection of a change in capacitance of one or more of the single second capacitors caused when a user touches one or more of the touch regions, and wherein in the active mode the single first capacitors are charged to allow the touch regions to be used for user input.

3. The capacitive touchscreen device of claim 1, wherein

the single first and second capacitors of each touch region are not shared by the other touch regions.

4. The capacitive touchscreen device of claim 1, wherein the controller is configured to detect a capacitive change in the plurality of the single second capacitors when a user touches one or more of the touch regions.

5. The capacitive touchscreen device of claim 4, wherein at least one of:

the controller is configured to detect a capacitive change of 5 picofarads or more;

the single first capacitors have a capacitance from 60 picofarads to 200 picofarads;

or

the single second capacitors have a capacitance from 10 picofarads to 60 picofarads.

6. The capacitive touchscreen device of claim 1, further comprising a plurality of single third capacitors coupled to areas on the touchscreen different than the touch regions, each of the single third capacitors having a smaller capacitance than an individual capacitance of any of the single first capacitors.

7. The capacitive touchscreen device of claim 6, wherein the capacitive touchscreen device is configured such that:

when the capacitive touchscreen device is in the standby mode, the single first capacitors are not charged while the single second and third capacitors are charged for allowing detection that a user has touched the touchscreen;

the single first capacitors are charged when the capacitive touchscreen device is in the active mode, for allowing the touch regions to be used for user input; and

the capacitive touchscreen device switches from the standby mode to the active mode in response to detection of a change in capacitance of any one or more of the single second and third capacitors caused when a user touches an area on the touchscreen coupled to the one or more single second and third capacitors.

8. The capacitive touchscreen device of claim 7, wherein the single second and third capacitors are configured such that there is detectable change in capacitance for switching the capacitive touchscreen device from the standby mode to the active mode when a user touches anywhere on the touchscreen.

9. The capacitive touchscreen device of claim 1, wherein the capacitive touchscreen device includes a two layer Indium Titanium Oxide (ITO) panel.

10. A thermostat comprising the capacitive touchscreen device of claim 1.

11. A controller for a heating ventilation and air conditioning (HVAC) system, the controller including the capacitive touchscreen device of claim 1.

12. The capacitive touchscreen device of claim 1, wherein the single second capacitors are not charged when the capacitive touchscreen device is operated in the active mode.

13. A method for operating a capacitive touchscreen device comprising a controller, a plurality of single first capacitors each having an individual unique input port to the controller, a plurality of single second capacitors connected in parallel and having a common input port to the controller that is separate from any of the first capacitor input ports, and a touchscreen having a plurality of mutually isolated touch regions, each said touch region being coupled one of the single first capacitors and one of the single second capacitors, each single second capacitor being different from each single first capacitor and having a smaller individual capacitance than an individual capacitance of any of the single first capacitors, the method comprising:

charging the single second capacitors without charging the single first capacitors when the capacitive touchscreen device is in a standby mode to reduce power consumption by the single first capacitors;

charging the first capacitors when the capacitive touchscreen device is in an active mode, wherein in the standby mode the single second capacitors are charged via the common input port and in the active mode the single first capacitors are charged via each corresponding individual unique input port;

scanning only the single first capacitors for a change in capacitance during the active mode to determine which touch region is being touched by a user; and

switching the capacitive touchscreen device from the standby mode to the active mode in response to detection of a change in capacitance of one or more of the single second capacitors by the controller.

14. The method of claim 13, wherein the method includes switching from the standby mode in which the single first capacitors are not charged to the active mode in which the single first capacitors are charged to allow the touch regions to be used for user input, in response to a detection of a change in capacitance of one or more of the single second capacitors caused when a user touches one or more of the touch regions.

15. The method of claim 13, further comprising

charging a plurality of single third capacitors coupled to areas on the touchscreen different than the touch regions, the single third capacitors each having a smaller individual capacitance than an individual capacitance of any of the first capacitors;

and

charging the single first capacitors in response to detection of a change in capacitance of any one or more of the single second and third capacitors.

16. The method of claim 15, wherein the single second and third capacitors are configured such that there is a detectable change in capacitance when a user touches anywhere on the touchscreen.

17. The method of claim 15, wherein the method includes:

charging the single second and third capacitors without charging the single first capacitors when the capacitive touchscreen device is in the standby mode, such that the single first capacitors are not charged until detection of a change in capacitance of any one or more of the single second and third capacitors; and

switching from the standby mode in which the single first capacitors are not charged to the active mode in which the single first capacitors are charged to allow the touch regions to be used for user input, in response to a detection of a change in capacitance of any one or more of the single second and third capacitors.

18. The method of claim 13, further comprising:

receiving a key code associated with a single first capacitor that has a capacitive change.

19. The method of claim 13, wherein the method includes charging the single first capacitors without charging the single second capacitors when the capacitive touchscreen device is in an active mode.

20. The method of claim 13, wherein the capacitive touchscreen device includes a two layer Indium Titanium Oxide (ITO) panel.