INTERACTIVE INPUT SYSTEM AND INFORMATION INPUT METHOD THEREFOR

1 . An interactive input system comprising:

at least one imaging device having a field of view looking into a region of interest and capturing images;

at least one pen tool comprising an accelerometer configured to measure acceleration of the pen tool and to generate acceleration data, the pen tool configured to wirelessly transmit the acceleration data; and

processing structure configured to process the images and acceleration data to determine the location of at least one pointer in the region of interest.

2 . The system of claim 1 , wherein the at least one imaging device comprises at least two imaging devices.

3 . The system of claim 2 , wherein the processing structure is configured to process the images by triangulation.

4 . The system of claim 1 , wherein the at least one pointer comprises at least one pen tool.

5 . The system of claim 4 , wherein the at least one pointer further comprises at least one finger.

6 . The system of claim 1 , wherein the pen tool is configured for wirelessly transmitting the measured acceleration data using any of an optical signal and a radio frequency signal.

7 . The system of claim 6 , wherein the optical signal is an infrared signal.

8 . The system of claim 1 , wherein the at least one imaging device comprises one imaging device.

9 . A pen tool for use with an interactive input system, the interactive input system comprising at least one imaging assembly capturing images of a region of interest, the interactive input system further comprising processing structure configured for locating a position of the pen tool when positioned in the region of interest, the pen tool comprising:

an accelerometer configured for measuring acceleration of the pen tool and generating acceleration data; and

a wireless unit configured for wirelessly transmitting the acceleration data.

10 . The pen tool of claim 9 , wherein the wireless unit is configured for wirelessly transmitting the acceleration data using any of an optical signal and a radio frequency signal.

11 . The pen tool of claim 6 , wherein the optical signal is an infrared signal.

12 . A method of inputting information into an interactive input system comprising at least one imaging assembly capturing images of a region of interest, the method comprising:

determining the position of at least two pointers in the region of interest, at least one of the at least two pointers being a pen tool comprising an accelerometer and transmitting accelerometer data to the system, the determining comprising processing image data captured by the at least one imaging assembly and accelerometer data received by the system.

13 . The method of claim 12 , further comprising:

determining that occlusion of one of the pointers has occurred;

calculating a first acceleration for each pen tool based on the accelerometer data received by the system;

calculating a second acceleration for each pointer based on image data captured by the at least one imaging assembly; and

calculating a respective region of prediction for each pen tool based on the first and second accelerations; and

determining a correct position for each pen tool by assessing whether the pen tool lies within the respective region of prediction.

14 . The method of claim 13 , wherein the at least one pointer further comprises at least one finger, the method further comprising:

determining a correct position for each finger based on the correct position for determined for each pen tool.

15 . The method of claim 13 , wherein the processing image data comprises triangulation.

16 . The method of claim 13 , wherein the pen tool is configured for wirelessly transmitting the accelerometer data using any of an optical signal and a radio frequency signal.

17 . The method of claim 16 , wherein the optical signal is an infrared signal.

18 . The pen tool of claim 9 , wherein the wireless unit wirelessly transmits the acceleration data only once instructed to do so by the interactive input system.