LOW POWER WAKEUP DETECTION CIRCUIT AND A PORTABLE ELECTRONIC DEVICE HAVING A LOW POWER WAKEUP DETECTION CIRCUIT

• US 20110080367A1
• Filed: 10/02/2009
• Published: 04/07/2011
• Est. Priority Date: 10/02/2009
• Status: Active Grant

• Current Assignee: Malikie Innovations Limited (Key Patent Innovations Limited)
• Original Assignee: Blackberry Limited
• Inventors: HOLBEIN, Marc Edward, MARCHAND, Rene Pierre, BERNARD, Christopher Dave
• Granted Patent: US 8,780,055 B2
• Time in Patent Office: Days
• US Class Current: 345/174
• CPC Class Codes: G06F 1/3215 Monitoring of peripheral devices
• CPC Class Codes: G06F 1/324 by lowering clock frequency
• CPC Class Codes: Y02D 10/00 Energy efficient computing, e.g. low power processors, power management or thermal management
• CPC Class Codes: Y02D 30/50 in wire-line communication networks, e.g. low power modes or reduced link rate

Abstract

The present disclosure provides a low power wakeup detection circuit and a portable electronic device having a low power wakeup detection circuit. In accordance with one embodiment, there is provided a portable electronic device, comprising: a housing; a controller received within the housing; a touch-sensitive display having a touch-sensitive overlay, the touch-sensitive display being mechanically constrained by the housing; at least one force sensing transducer located below the touch-sensitive display on an opposite side to the touch-sensitive overlay, the at least one force sensing transducer being connected to the controller and measuring forces applied to the touch-sensitive display; wherein the controller is configured for: initiating a sleep mode from a full power mode in response to a trigger; when in the sleep mode, reading force data measured by the at least one force sensing transducer at a reduced duty cycle relative to the full power mode, comparing the force data to a wakeup force threshold, and returning to the full power mode from the sleep mode when the force data is greater than the wakeup force threshold.

Claims

1. A portable electronic device, comprising:

a housing;

a controller received within the housing;

a touch-sensitive display having a touch-sensitive overlay, the touch-sensitive display being mechanically constrained by the housing;

at least one force sensing transducer located below the touch-sensitive display on an opposite side to the touch-sensitive overlay, the at least one force sensing transducer being connected to the controller and measuring forces applied to the touch-sensitive display;

wherein the controller is configured for;

initiating a sleep mode from a full power mode in response to a trigger;

when in the sleep mode, reading force data measured by the at least one force sensing transducer at a reduced duty cycle relative to the full power mode, comparing the force data to a wakeup force threshold, and returning to the full power mode from the sleep mode when the force data is greater than the wakeup force threshold.

2. The device of claim 1, comprising a plurality of force sensing transducers, wherein a sum of the output of the force sensing transducers is read by the controller and compared to the wakeup force threshold.

3. The device of claim 2, wherein the force sensing transducers are force sensing resistors.

4. The device of claim 3, wherein the force sensing transducers comprise four force sensing resistors, each force sensing resistor being located near a respective corner of the touch-sensitive display.

5. The device of claim 4, wherein the force sensing resistors are summed using a multi-port switch having a switch for each of the force sensing resistors, wherein the multi-port switch is controlled by the controller, wherein a respective switch for each of the force sensing resistors is closed during an active portion of the sleep duty cycle in which force data is read, and wherein the respective switch for each of the force sensing resistors is open during the inactive portion in which force data is not read.

6. The device of claim 5, wherein the duration of the reduced duty cycle is selected to match a duration for which force must be applied to the touch-sensitive display to return to the full power mode.

7. The device of claim 5, wherein the reduced duty cycle is set so that the force sensing resistors are powered-on and read by the controller for approximately 1 millisecond every 100 milliseconds.

8. The device of claim 1, comprising a plurality of force sensing transducers, wherein a particular group of force sensing transducers in the plurality of force sensing transducers are read by the controller and compared to the wakeup force threshold.

9. The device of claim 8, wherein the particular group of force sensing transducers in the plurality of force sensing transducers is selected based on an orientation of the portable electronic device.

10. The device of claim 1, further comprising:

a system clock and a sleep clock each connected to the controller, the sleep clock having a lower frequency than the system clock, wherein the controller is configured for switching from the system clock to the sleep clock in the sleep mode and powering down the system clock in the sleep mode.

11. The device of claim 1, further comprising:

a least one piezoelectric element connected to the controller, wherein the piezoelectric element is resiliently biased and located beneath a back side of the touch-sensitive display opposite to a touch-sensitive overlay of the touch-sensitive display, the movement of the touch-sensitive display being caused by modulating a charge of the piezoelectric element thereby providing haptic feedback which simulates the collapse of a dome-type switch.

12. A control circuit, comprising:

a controller having a full power duty cycle and a slower sleep mode duty cycle, the full power duty cycle and sleep mode duty cycle each having an active portion in which data is read and an inactive portion in which data is not read;

a plurality of force sensing transducers for measuring force data which are connected to the controller;

a multi-port switch which sums the force data output of the plurality of force sensing transducers, the multi-port switch having a switch for each of the force sensing transducers, a respective switch for each of the force sensing transducers being closed during an active portion of the sleep duty cycle and the respective switch for each of the force sensing transducers being open during the inactive portion of the sleep duty cycle; and

a comparator for comparing the summed force data from the multi-port switch to a wakeup force threshold;

wherein the controller is configured to wake from a sleep mode and return to a full power mode when the summed force data is greater than the wakeup force threshold.

13. The circuit of claim 12, wherein the force sensing transducers are force sensing resistors.

14. The circuit of claim 13, wherein the force sensing transducers comprise four force sensing resistors, each force sensing resistor being located behind a touch-sensitive display of a portable electronic device near a respective corner of the touch-sensitive display.

15. The circuit of claim 12, wherein the duration of the sleep duty cycle is selected to match a duration for which force must be applied to the touch-sensitive display to return to the full power mode.

16. The circuit of claim 12, wherein the sleep duty cycle is set so that the force sensing transducers are powered-on and read by the controller for approximately 1 millisecond every 100 milliseconds.

17. The circuit of claim 12, further comprising:

a system clock and sleep clock having a lower frequency than the system clock, wherein the controller is configured for switching from the system clock to the sleep clock in the sleep mode and powering down the system clock.

18. The circuit of claim 12, further comprising:

a plurality of piezoelectric elements connected to the controller, the piezoelectric elements being resiliently biased and located beneath the back side of the touch-sensitive display opposite to the touch-sensitive overlay of the touch-sensitive display, the movement of the touch-sensitive display being caused by modulating the charge of the piezoelectric elements thereby providing haptic feedback which simulates the collapse of a dome-type switch.

19. The circuit of claim 12, wherein the comparator is a digital comparator circuit which triggers an interrupt to the controller when the force data is greater than the wakeup force threshold.

20. The circuit of claim 12, wherein the comparator is an analog-to-digital converter of the controller which detects input signals represent force data greater than the wakeup force threshold.