Power-saving method for an optical navigation device

• US 20050110746A1
• Filed: 11/25/2003
• Published: 05/26/2005
• Est. Priority Date: 11/25/2003
• Status: Abandoned Application

• Current Assignee: Alpha Hou
• Original Assignee: Alpha Hou
• Inventors: Hou, Alpha
• Application Number:
  US10/720,243
• Publication Number:
  US 20050110746A1
• Time in Patent Office: Days
• US Class Current: 345/156
• CPC Class Codes: G06F 1/3203 Power management, i.e. event-based initiation of a power-saving mode
• CPC Class Codes: G06F 1/325 Power saving in peripheral device
• CPC Class Codes: G06F 1/3259 Power saving in cursor control device, e.g. mouse, joystick, trackball
• CPC Class Codes: G06F 3/0317 in co-operation with a patterned surface, e.g. absolute position or relative movement detection for an optical mouse or pen positioned with respect to a coded surface
• CPC Class Codes: G06F 3/03543 Mice or pucks G06F3/03541 takes precedence
• CPC Class Codes: Y02D 10/00 Energy efficient computing, e.g. low power processors, power management or thermal management

Abstract

A power-saving method for an optical navigation device is proposed, wherein the image capture frame rate of a sensor is controlled according to the moving speed of the optical navigation device. The image capture frame rate is determined based on the variations of a horizontal displacement and a vertical displacement of the optical navigation device for saving power. Moreover, when the optical navigation device is in the sleeping mode, it is not necessary to generate a current to drive the sensor to monitor whether the optical navigation device moves or not. A displacement detector (e.g., a mechanical displacement trigger) is used instead to generate a current for breaking off the sleeping mode to accomplish the power-saving object.

Claims

1. A power-saving method for an optical navigation device comprising the steps of:

using a sensor to capture a first image and a second image;

comparing said first image and said second image;

generating a horizontal displacement of a parallel axis and a vertical displacement of a vertical axis;

controlling the image capture frame rate of said sensor according to the variations of said horizontal displacement and said vertical displacement; and

outputting said horizontal displacement and said vertical displacement in an output period.

2. The power-saving method for an optical navigation device as claimed in claim 1, wherein said first image is the image captured by said sensor when said optical navigation device hasn'"'"'t moved yet.

3. The power-saving method for an optical navigation device as claimed in claim 1, wherein said first and second images are compared by a digital signal processor, a central processing unit or a controller.

4. The power-saving method for an optical navigation device as claimed in claim 1, wherein the image capture frame rate of said sensor is increased when the variations of said horizontal displacement and said vertical displacement are larger than an upper threshold.

5. The power-saving method for an optical navigation device as claimed in claim 1, wherein the image capture frame rate of said sensor is decreased when the variations of said horizontal displacement and said vertical displacement are smaller than a lower threshold.

6. The power-saving method for an optical navigation device as claimed in claim 1, wherein the image capture frame rate of said sensor is maintained when the variations of said horizontal displacement and said vertical displacement are larger than a lower threshold and smaller than an upper threshold.

7. The power-saving method for an optical navigation device as claimed in claim 1, wherein said second image is the image captured by said sensor after a predefined frame rate.

8. The power-saving method for an optical navigation device as claimed in claim 7, wherein said frame rate is proportional to said output period.

9. A power-saving method for an optical navigation device, said method accomplishing the power-saving object through a displacement sensor, said method comprising the steps of:

using a sensor to capture a first image and a second image;

comparing said first image and said second image to make sure there is no displacement as long as said first image is equal to said second image;

lasting for a first waiting period;

or

lasting for a second waiting period;

or

entering a sleeping mode;

inputting a current via said displacement sensor to break off said sleeping mode; and

starting to capture images with said sensor.

10. The power-saving method for an optical navigation device as claimed in claim 9, wherein said sensor won'"'"'t be driven to detect whether said optical navigation device moves or not during said sleeping mode.

11. The power-saving method for an optical navigation device as claimed in claim 9, wherein said displacement sensor can be a mechanical structure, a semiconductor micro-electro-mechanical (MEMS) structure, an assembly of the above two structures, or any structure capable of detecting displacement.