Range and speed finder

1. A personal electronic device, comprising:

an automatic focus system adapted to focus an image of an object through a lens of the device and onto an imager thereof; and,

a processor in communication with the automatic focus system and adapted to compute a distance of the object from the device as a function of a focal length of the lens and a distance between the lens and the imager.

2. The personal electronic device of claim 1 , wherein the processor is adapted to detect a speed of the object using the automatic focus system.

3. The personal electronic device of claim 1 , wherein the processor is adapted to measure a dimension of the object using the automatic focus system.

4. The personal electronic device of claim 1 , wherein the personal electronic device is selected from the group consisting of:

a portable computer;

a laptop computer;

a notebook computer;

a pocket personal computer (pocket PC);

a personal digital assistant (PDA); and,

a mobile telephone.

5. A range finder configured to determine a distance to an object relative to a personal electronic device, the range finder comprising:

a lens having a focal length and adapted to pass light received at the personal electronic device;

an imager adapted to capture images from the light passed through the lens;

an assembly adapted to move the lens relative to the linger to focus a first image of the object an the imager;

a sensor adapted to detect a first position of the lens relative to the imager when the object is focused on the imager, wherein the imager is adapted to capture the first image of the object when the object is focused on the imager, and,

a processor adapted to calculate a first distance to the object from the device as a function of the focal length of the lens and the distance between the lens and the imager.

6. The range finder of claim 5 , wherein the processor is adapted to calculate a dimension of the object using the first distance, a field of view associated with the range finder, and the first image.

7. The range finder of claim 5 , wherein the range finder is adapted to measure a speed of the object relative to the personal electronic device, wherein:

the imager is adapted to capture a second image of the object when the object is focused on the imager; and,

the processor is adapted to calculate:

a distance traveled by the object using the first distance, a field of view associated with the range finder, the first image, and the second image; and,

a speed of the object relative to the personal electronic device using the calculated distance traveled by the object and a time period elapsing between the capture of the first and second images.

8. The range finder of claim 5 , wherein the range finder is adapted to measure a speed of the object relative to the personal electronic device, wherein:

the sensor is adapted to detect a second position of the lens relative to the imager when the object is focused on the imager;

the imager is adapted to capture a second image of the object when the object is focused on the imager; and,

the processor is adapted to calculate a second distance to the object using the detected second position of the lens, and adapted to calculate the speed of the object relative to the personal electronic device using the first distance, second distance, and a time period elapsing between the focusing of the first and second images.

9. The range finder of claim 5 , wherein the assembly comprises:

a stage, wherein the lens is in a fixed position relative to the stage; and,

an actuator adapted to translate the stage relative to the imager.

10. The range finder of claim 9 , wherein the actuator is a Lorentz motor.

11. The range finder of claim 9 , wherein the actuator is a micro-electro-mechanical systems (MEMS) device.

12. The range finder of claim 5 , wherein the range finder is embedded in the personal electronic device.

13. The range finder of claim 5 , wherein the personal electronic device is selected from the group consisting of:

a portable computer;

a laptop computer;

a notebook computer;

a pocket personal computer (pocket PC);

a personal digital assistant (PDA); and,

a mobile telephone.

14. A method of determining a distance to an object from a personal electronic device, the method comprising:

receiving light from the object through an aperture of the personal electronic device;

passing the light through a lens of the device, the lens having a focal length;

focusing the light from the object passed through the lens onto an imager of the device;

capturing an image of the object with the imager;

detecting a distance between the lens and the imager when the image is captured; and,

calculating the distance to the object from the device as a function of the focal length of the lens and the detected distance between the lens and the imager.

15. The method of claim 14 , further comprising calculating a dimension of the object using the distance, a field of view, and the image.

16. The method of claim 14 , further comprising:

processing the image to determine whether the image is focused on an imager; and,

if the image is not focused on the imager;

moving the lens relative to the imager, and,

repeating the capturing, processing, and moving until the image is focused on the imager.

17. A method of determining a speed of an object relative to a personal electronic device, the method comprising:

receiving light through an aperture of the electronic device;

passing the light through a lens;

moving the lens to focus the object;

capturing a first image of the object from the light passed through the lens;

detecting a first position of the lens when the first image is captured;

calculating a first distance to the object using the detected first position;

capturing a second image of the object from the light passed through the lens;

calculating a time period elapsing between the capturing of the first and second images; and,

calculating a speed of the object using the time period.

18. The method of claim 17 , further comprising calculating a distance traveled by the object using the first distance, a field of view, the first image, and the second image, wherein the calculating a speed further uses the calculated distance traveled by the object.

19. The method of claim 17 , further comprising:

moving the lens again to focus the object;

detecting a second position of the lens when the second image is captured; and,

calculating a second distance to the object using the second detected position, wherein the calculating a speed further uses the first distance and second distance.

20. The method of claim 17 , wherein the first and second lens positions correspond to positions of the lens relative to an imager.