System and method for minimizing power consumption for an object sensor

• US 7,643,950 B1
• Filed: 12/01/2005
• Issued: 01/05/2010
• Est. Priority Date: 12/01/2005
• Status: Expired

• Current Assignee: Synaptics Incorporated, National Semiconductor Corporation (Texas Instruments, Inc.)
• Original Assignee: Validity Sensors Incorporated (Synaptics Incorporated), National Semiconductor Corporation (Texas Instruments, Inc.)
• Inventors: Getzin, Lawrence, Jandu, Jaswinder S., Nelson, Richard B., Erhart, Richard Alexander
• Primary Examiner(s): BHAT, ADITYA S
• Application Number:
  US11/291,639
• Time in Patent Office: 1,496 Days
• Field of Search: 702/19, 702/60, 702/168, 340/5.53, 340/5.83
• US Class Current: 702/60
• CPC Class Codes: G06V 40/13 Sensors therefor

Abstract

A system and method is disclosed for minimizing power consumption of a sensor unit that is capable of detecting an object. Main circuitry operates the sensor unit in a high power mode of operation when the sensor unit detects an object. Low power control circuitry operates the sensor unit in a low power mode of operation when the sensor unit does not detect an object within a pre-determined period of time. The low power control circuitry also comprises a counter to periodically determine when to restore the sensor unit to a high power mode of operation. One advantageous embodiment of the sensor unit is a fingerprint sensor unit for detecting a finger to obtain fingerprint information.

Claims

1. An apparatus for reducing or minimizing power consumption of a sensor unit that is configured to detect and scan an object only when the sensor unit is operating in a high power mode of operation, the apparatus comprising:

main circuitry having a main power supply, wherein the main circuitry operates the sensor unit in the high power mode of operation; and

low power control circuitry having a second power supply, wherein the low power control circuitry operates the sensor unit in a low power mode of operation when the sensor unit does not detect the object within a specified period of time.

2. The apparatus as set forth in claim 1, wherein the main circuitry operates the sensor unit in the high power mode of operation when the sensor unit detects the object.

3. The apparatus as set forth in claim 1, wherein the low power control circuitry comprises a counter configured to count for the specified period of time.

4. The apparatus as set forth in claim 1, wherein the second power supply continually supplies power to the low power control circuitry.

5. An apparatus for reducing or minimizing power consumption of a sensor unit that is capable of detecting and scanning an object only when the sensor unit is operating in a high power mode of operation, the apparatus comprising:

main circuitry that operates the sensor unit in the high power mode of operation;

low power control circuitry that operates the sensor unit in a low power mode of operation;

a first power supply coupled to the low power control circuitry that continually supplies power to the low power control circuitry;

a second power supply coupled to the main circuitry that supplies power to the main circuitry only when the main circuitry is operating the sensor unit in the high power mode of operation; and

a sensor controller that places the sensor unit in the low power mode of operation when the sensor unit does not detect the object within a specified period of time.

6. The apparatus as set forth in claim 5, wherein the low power control circuitry comprises:

a counter configured to count for the specified period of time.

7. The apparatus as set forth in claim 6, wherein the low power control circuitry further comprises:

a low power mode memory unit in which the sensor controller stores status information from the sensor unit when the sensor controller places the sensor unit in the low power mode of operation.

8. The apparatus as set forth in claim 6, wherein the low power control circuitry further comprises:

a low power sequencer that powers down the main circuitry when the sensor controller places the sensor unit in the low power mode of operation.

9. An apparatus for reducing or minimizing power consumption of a sensor unit that is capable of detecting and scanning an object only when the sensor unit is operating in a high power mode of operation, the apparatus comprising:

main circuitry that operates the sensor unit in the high power mode of operation; and

low power control circuitry that operates the sensor unit in a low power mode of operation, wherein the low power control circuitry includes;

a sensor controller that places the sensor unit in the low power mode of operation when the sensor unit does not detect the object within a first specified period of time; and

a low power sequencer that powers down the main circuitry when the sensor controller places the sensor unit in the low power mode of operation;

wherein the low power sequencer powers down the main circuitry by disabling a power supply that supplies power to the main circuitry.

10. The apparatus as set forth in claim 9, wherein the low power control circuitry further comprises:

a counter that counts for a second specified period of time to determine when to activate the sensor controller to power up the sensor unit and the main circuitry after the sensor unit has been placed in the low power mode of operation.

11. An apparatus for reducing or minimizing power consumption of a fingerprint sensor unit that is capable of detecting and scanning a finger, the apparatus comprising:

a fingerprint sensor unit that detects and scans the finger only when the sensor unit is operating in a high power mode of operation;

main circuitry having a main power supply, wherein the main circuitry operates the fingerprint sensor unit in the high power mode of operation when the fingerprint sensor unit detects the finger; and

low power control circuitry having a second power supply, wherein the low power control circuitry operates the fingerprint sensor unit in a low power mode of operation when the fingerprint sensor unit does not detect the finger within a specified period of time.

12. The apparatus as set forth in claim 11, wherein the low power control circuitry comprises:

a sensor controller;

a low power sequencer;

a low power mode memory unit; and

a counter.

13. A method for reducing or minimizing power consumption of a sensor unit that is capable of detecting and scanning an object, the method comprising the steps of:

detecting and scanning the object using the sensor unit only when the sensor unit is operating in a high power mode of operation;

operating main circuitry powered by a main power supply to operate the sensor unit in the high power mode of operation when the sensor unit detects the object; and

operating low power control circuitry powered by a second power supply to operate the sensor unit in a low power mode of operation when the sensor unit does not detect the object within a specified period of time.

14. The method as set forth in claim 13 further comprising the step of:

continually supplying power to the low power control circuitry with the second power supply.

15. A method for reducing or minimizing power consumption of a sensor unit that is capable of detecting and scanning an object, the method comprising the steps of:

operating main circuitry to operate the sensor unit in a high power mode of operation when the sensor unit detects and scans the object only in the high power mode of operation;

operating low power control circuitry to operate the sensor unit in a low power mode of operation when the sensor unit does not detect the object within a specified period of time;

continually supplying power to the low power control circuitry from a first power supply coupled to the low power control circuitry; and

supplying power to the main circuitry from a second power supply coupled to the main circuitry only when the main circuitry is operating in the high power mode of operation.

16. The method as set forth in claim 15, further comprising the step of:

operating a sensor controller within the low power control circuitry to place the sensor unit in the low power mode of operation when the sensor unit does not detect the object within the specified period of time.

17. The method as set forth in claim 16, further comprising the step of:

operating the sensor controller to store status information from the sensor unit in a low power mode memory unit when the sensor controller places the sensor unit in the low power mode of operation.

18. The method as set forth in claim 16, further comprising the step of:

powering down the main circuitry with a low power sequencer when the sensor controller places the sensor unit in the low power mode of operation.

19. The method as set forth in claim 18, wherein the step of powering down the main circuitry comprises:

disabling the second power supply.

20. The method as set forth in claim 16, further comprising the steps of:

operating a counter to count for a second specified period of time to determine when to activate the sensor controller to power up the sensor unit and the main circuitry after the sensor unit has been placed in the low power mode of operation; and

powering up the sensor unit and the main circuitry after the counter has counted for the second specified period of time.